CN109151236A - Calling route selection method and call route selecting system - Google Patents

Abstract

The invention discloses a call route selection method and a call route selection system. Including: when the first terminal under the jurisdiction of the first telephone switching network end office calls the second terminal under the jurisdiction of the second telephone switching network end office, the softswitch device obtains the current first circuit state information of the first relay gateway, and according to the current The first circuit state information selects the first relay gateway as the relay gateway for carrying the call between the first terminal and the second terminal; or, when the first switched telephone network end office is under the jurisdiction of the first terminal to call the second switched telephone network When the end office is under the jurisdiction of the second terminal, the softswitch device obtains the current second circuit state information of the second relay gateway, and selects the second relay gateway as the one carrying the first terminal and the second terminal according to the current second circuit state information. Trunk gateway for calls between. The invention effectively avoids the phenomenon that users under the PSTN end office cannot make or answer calls when the relay gateway fails, and improves the user experience.

Description

Call routing method and call routing system

technical field

The present invention relates to the field of communication technologies, in particular to a call routing method and a call routing system.

Background technique

The basic meaning of Soft Switch is to separate the call control function from the media gateway (transport layer), establish a separate plane for control, switching and software programmable functions, and realize the basic call control function mainly through software, so as to achieve Separation of call transport and call control. The network of the softswitch architecture mainly includes a softswitch device, a trunk gateway (TG for short), a signaling gateway (SG for short) and an access gateway (AG for short). Among them, the soft switch equipment mainly provides functions such as connection control, translation and routing, gateway management, call control, bandwidth management, signaling, security and call detail records; TG is used to complete media stream conversion under the control of the Soft switch. and other functions, mainly used for relay access, TG provides media mapping and transcoding functions between the IP network and the public circuit switching network (PSTN), that is, terminating circuit switching network facilities (trunk lines, loops, etc.), converting media The stream is packetized and the packetized media stream is transmitted on the packet network; AG is used to directly access the user terminal to the IP packet network, such as ordinary analog users, ISDN, etc., to provide media mapping and code conversion between the IP network and the user terminal. , packetize the media stream and transmit the packetized media stream on the packet network; SG is used to complete the signaling conversion function between the circuit-switched network and the packet-switched network (based on IP), and the SG can effectively realize the circuit-switched network and packet Intercommunication of signaling between networks, SG receives and sends standard SS7 signaling messages on the circuit-switched network side, and adopts the IETF signaling transport working group (SIGTRAN) standard adaptation layer protocol and transport layer protocol on the packet network side. Strong capability, complete functions and high reliability.

At present, in the traditional call routing configuration, a public circuit switched network (PSTN) end office can only access one trunk gateway. When the trunk gateway fails, all users under the PSTN end office cannot make calls normally. and answering calls, resulting in reduced user experience.

SUMMARY OF THE INVENTION

The invention provides a call routing method and a call routing system, which are used to effectively avoid the phenomenon that users under the PSTN end office cannot make or answer calls when the relay gateway fails, and improve user experience.

In order to achieve the above object, the present invention provides a call routing method, the call routing method includes:

When the first terminal under the jurisdiction of the first telephone switching network end office calls the second terminal under the jurisdiction of the second telephone switching network end office, the softswitch device obtains the current first circuit state information of the first relay gateway;

The softswitch device selects the first relay gateway as the relay gateway for carrying the call between the first terminal and the second terminal according to the current first circuit state information; or,

When the first terminal under the jurisdiction of the first telephone switching network end office calls the second terminal under the jurisdiction of the second telephone switching network end office, the softswitch device obtains the current second circuit status information of the second relay gateway;

The softswitch device selects the second relay gateway as the relay gateway for carrying the call between the first terminal and the second terminal according to the current second circuit state information; or,

When the first terminal under the jurisdiction of the first telephone switching network end office calls the second terminal under the jurisdiction of the second telephone switching network end office, the softswitch device obtains the current third circuit status information of the first relay gateway;

The softswitch device acquires the current fourth circuit state information of the second relay gateway;

The softswitch device selects the first relay gateway and the second relay gateway as the relay gateways carrying the call between the first terminal and the second terminal according to the current third circuit state information and the current fourth circuit state information.

Optionally, the current first circuit state information includes information used to determine that the circuit states of the first trunk gateway accessing the first telephone switching network end office and the second telephone switching network end office are both idle states, and the softswitch is in an idle state. Before the device acquires the current first circuit state information of the first relay gateway, it further includes:

The softswitch device sends a first idle circuit query request to the first relay gateway;

The first relay gateway, according to the first idle circuit query request, judges whether the state of the circuit connected to the end office of the first telephone switching network is the idle state and whether the state of the circuit connected to the end office of the second telephone switching network is the idle state;

If the first relay gateway determines that the state of the circuit connected to the end office of the first telephone switching network is the idle state and the state of the circuit that is connected to the end office of the second telephone switching network is the idle state, it returns to the softswitch device. the current first circuit state information.

Optionally, the current second circuit state information includes information used to determine that the circuit states of the second trunk gateway accessing the first telephone switching network end office and the second telephone switching network end office are both idle states, and the softswitch is in an idle state. Before the device acquires the current second circuit state information of the second relay gateway, it further includes:

The softswitch device sends a first idle circuit query request to the first relay gateway;

The first relay gateway, according to the first idle circuit query request, judges whether the state of the circuit connected to the end office of the first telephone switching network is the idle state and whether the state of the circuit connected to the end office of the second telephone switching network is the idle state;

If the first relay gateway determines that at least one of the circuit state of the end office connected to the first telephone switching network and the circuit state of the end office of the second telephone switching network is a non-idle state, it will send a message to the softswitch device. Returns no simultaneous connection capability information;

The softswitch device sends a second idle circuit query request to the second relay gateway according to the information that the first relay gateway does not have simultaneous connection capability;

According to the second idle circuit query request, the second relay gateway judges whether the state of the circuit connected to the end office of the first telephone switching network is the idle state and whether the state of the circuit connected to the end office of the second telephone switching network is the idle state;

If the second relay gateway determines that the state of the circuit connected to the end office of the first telephone switching network is in the idle state and the state of the circuit connected to the end office of the second telephone switching network is the idle state, it sends a message to the softswitch device. the current second circuit state information.

Optionally, the current third circuit state information includes information used to determine that the circuit state in which the first trunk gateway accesses the first telephone switching network end office is an idle state, and the current fourth circuit state information includes information used to determine the second intermediate state. information that the circuit status of the end office of the second telephone switching network when the gateway is connected to the second telephone switching network is idle;

Before acquiring the current third circuit state information of the first relay gateway, the softswitch device further includes:

The softswitch device sends a first idle circuit query request to the first relay gateway;

The first relay gateway, according to the first idle circuit query request, judges whether the state of the circuit connected to the end office of the first telephone switching network is the idle state and whether the state of the circuit connected to the end office of the second telephone switching network is the idle state;

If the first relay gateway determines that the state of the circuit connected to the end office of the first telephone switching network is an idle state and the state of the circuit that is connected to the end office of the second telephone switching network is a non-idle state, it will report to the softswitch device. sending the current third circuit state information;

Before acquiring the current fourth circuit state information of the second relay gateway, the softswitch device further includes:

The softswitch device sends a second idle circuit query request to the second relay gateway;

According to the second idle circuit query request, the second relay gateway judges whether the state of the circuit connected to the end office of the first telephone switching network is the idle state and whether the state of the circuit connected to the end office of the second telephone switching network is the idle state;

If the second relay gateway determines that the state of the circuit connected to the end office of the first telephone switching network is in the non-idle state and the state of the circuit connected to the end office of the second telephone switching network is the idle state, it will send the information to the softswitch device. Sending the current fourth circuit state information.

Optionally, the current third circuit state information includes information used to determine that the circuit state in which the first trunk gateway accesses the end office of the second telephone switching network is an idle state, and the current fourth circuit state information includes information used to determine the second intermediate state. information that the circuit state of the end office of the first telephone switching network when the gateway is connected to the first telephone switching network is an idle state;

Before acquiring the current third circuit state information of the first relay gateway, the softswitch device further includes:

The softswitch device sends a first idle circuit query request to the first relay gateway;

The first relay gateway, according to the first idle circuit query request, judges whether the state of the circuit connected to the end office of the first telephone switching network is the idle state and whether the state of the circuit connected to the end office of the second telephone switching network is the idle state;

If the first relay gateway determines that the state of the circuit connected to the end office of the first telephone switching network is in a non-idle state and the state of the circuit connected to the end office of the second telephone switching network is an idle state, it will send a message to the softswitch device. sending the current third circuit state information;

Before acquiring the current fourth circuit state information of the second relay gateway, the softswitch device further includes:

The softswitch device sends a second idle circuit query request to the second relay gateway;

According to the second idle circuit query request, the second relay gateway judges whether the state of the circuit connected to the end office of the first telephone switching network is the idle state and whether the state of the circuit connected to the end office of the second telephone switching network is the idle state;

If the second relay gateway determines that the state of the circuit connected to the end office of the first telephone switching network is in an idle state and the state of the circuit connected to the end office of the second telephone switching network is a non-idle state, it will report to the softswitch device. Sending the current fourth circuit state information.

In order to achieve the above object, the present invention provides a call routing system, the call routing system includes a soft switch device, a first telephone switching network end office, a first terminal, a second telephone switching network end office, a second terminal, a first relay gateway and a second relay gateway;

The softswitch device is used to obtain the current first circuit state information of the first relay gateway when the first terminal under the jurisdiction of the first telephone switching network end office calls the second terminal under the jurisdiction of the second telephone switching network end office; a circuit state information, selecting the first relay gateway as the relay gateway for carrying the call between the first terminal and the second terminal; or,

The softswitch device is used to obtain the current second circuit status information of the second relay gateway when the first terminal under the jurisdiction of the first telephone switching network end office calls the second terminal under the jurisdiction of the second telephone switching network end office; Two circuit status information, select the second relay gateway as the relay gateway that carries the call between the first terminal and the second terminal; or,

The softswitch device is used to obtain the current third circuit status information of the first relay gateway when the first terminal under the jurisdiction of the first telephone switching network end office calls the second terminal under the jurisdiction of the second telephone switching network end office; obtain the second terminal The current fourth circuit state information of the relay gateway; according to the current third circuit state information and the current fourth circuit state information, the first relay gateway and the second relay gateway are selected as the bearer between the first terminal and the second terminal. The trunk gateway for calls.

Optionally, the current first circuit state information includes information used to determine that the circuit states of the first trunk gateway accessing the first telephone switched network end office and the second telephone switched network end office are both idle states;

The softswitch device is further configured to send a first idle circuit query request to the first relay gateway;

The first relay gateway is used to judge whether the state of the circuit connected to the end office of the first telephone switching network is an idle state and whether the state of the circuit connected to the end office of the second telephone switching network is an idle state according to the first idle circuit query request If it is judged that the state of the circuit accessing the end office of the first telephone switching network is an idle state and the state of the circuit accessing the end office of the second telephone switching network is an idle state, return the current first circuit to the softswitch device status information.

Optionally, the current second circuit state information includes information used to determine that the circuit states of the second trunk gateway accessing the first telephone switched network end office and the second telephone switched network end office are both idle states;

The softswitch device is further configured to send a first idle circuit query request to the first relay gateway;

The first relay gateway is used to judge whether the state of the circuit connected to the end office of the first telephone switching network is an idle state and whether the state of the circuit connected to the end office of the second telephone switching network is an idle state according to the first idle circuit query request If it is judged that at least one of the circuit states of the end office of the first telephone switching network and the circuit state of the end office of the second telephone switching network is a non-idle state, it returns to the softswitch equipment that it does not have the ability to connect at the same time information;

The softswitch device is further configured to send a second idle circuit query request to the second relay gateway according to the information that the first relay gateway does not have simultaneous connection capability;

The second relay gateway is used to judge whether the state of the circuit connected to the end office of the first telephone switching network is idle and whether the state of the circuit connected to the end office of the second telephone switching network is idle according to the second idle circuit query request ; If it is judged that the state of the circuit accessing the end office of the first telephone switching network is an idle state and the state of the circuit accessing the end office of the second telephone switching network is an idle state, send the current second circuit to the softswitch device status information.

Optionally, the current third circuit state information includes information used to determine that the circuit state in which the first trunk gateway accesses the first telephone switching network end office is an idle state, and the current fourth circuit state information includes information used to determine the second intermediate state. information that the circuit status of the end office of the second telephone switching network when the gateway is connected to the second telephone switching network is idle;

The softswitch device is further configured to send a first idle circuit query request to the first relay gateway;

The first relay gateway is used to judge whether the state of the circuit connected to the end office of the first telephone switching network is an idle state and whether the state of the circuit connected to the end office of the second telephone switching network is an idle state according to the first idle circuit query request ; If it is judged that the state of the circuit accessing the end office of the first telephone switching network is an idle state and the state of the circuit accessing the end office of the second telephone switching network is a non-idle state, send the current third circuit status information;

The softswitch device is further configured to send a second idle circuit query request to the second relay gateway;

The second relay gateway is used to judge whether the state of the circuit connected to the end office of the first telephone switching network is idle and whether the state of the circuit connected to the end office of the second telephone switching network is idle according to the second idle circuit query request If it is judged that the state of the circuit accessing the end office of the first telephone switching network is a non-idle state and the state of the circuit accessing the end office of the second telephone switching network is an idle state, send the current fourth to the softswitch device. circuit status information.

Optionally, the current third circuit state information includes information used to determine that the circuit state in which the first trunk gateway accesses the end office of the second telephone switching network is an idle state, and the current fourth circuit state information includes information used to determine the second intermediate state. information that the circuit state of the end office of the first telephone switching network when the gateway is connected to the first telephone switching network is an idle state;

The softswitch device is further configured to send a first idle circuit query request to the first relay gateway;

The first relay gateway is used to judge whether the state of the circuit connected to the end office of the first telephone switching network is an idle state and whether the state of the circuit connected to the end office of the second telephone switching network is an idle state according to the first idle circuit query request If it is judged that the state of the circuit accessing the end office of the first telephone switching network is a non-idle state and the state of the circuit accessing the end office of the second telephone switching network is an idle state, send the current third circuit status information;

The softswitch device is further configured to send a second idle circuit query request to the second relay gateway;

The second relay gateway is used to judge whether the state of the circuit connected to the end office of the first telephone switching network is idle and whether the state of the circuit connected to the end office of the second telephone switching network is idle according to the second idle circuit query request ; If it is judged that the circuit state of the end office accessing the first telephone switching network is an idle state and the circuit state accessing the end office of the second telephone switching network is a non-idling state, send the current fourth to the softswitch device. circuit status information.

The present invention has the following beneficial effects:

In the technical scheme of the call routing method and the call routing system provided by the present invention, the first telephone switching network end office and the second telephone switching network end office are connected to the first trunk gateway and the second trunk through different circuits gateway, when a user under the end office of the first telephone switching network and a user under the end office of the second telephone switching network make a call, the softswitch device selects the first relay gateway as the first terminal according to the current first circuit state information the relay gateway for the call between the first terminal and the second terminal, or the softswitch device selects the second relay gateway as the relay gateway for carrying the call between the first terminal and the second terminal according to the current second circuit state information, Alternatively, the softswitch device selects the first relay gateway and the second relay gateway as the relay gateways carrying the call between the first terminal and the second terminal according to the current third circuit state information and the current fourth circuit state information. This effectively avoids the phenomenon that users under the PSTN end office cannot make or receive calls when the relay gateway fails, improving user experience.

Description of drawings

1A is a flowchart of a call routing method according to Embodiment 1 of the present invention;

FIG. 1B is a flowchart of another call routing method according to Embodiment 1 of the present invention;

1C is a flowchart of another call routing method provided by Embodiment 1 of the present invention;

2 is a flowchart of a call routing method according to Embodiment 2 of the present invention;

FIG. 3 is a schematic structural diagram of a call routing system according to Embodiment 3 of the present invention.

Detailed ways

In order to make those skilled in the art better understand the technical solutions of the present invention, the call routing method and the call routing system provided by the present invention are described in detail below with reference to the accompanying drawings.

FIG. 1A is a flowchart of a call routing method according to Embodiment 1 of the present invention. As shown in FIG. 1A , the call routing method includes:

Step 101a: When the first terminal under the jurisdiction of the first telephone switching network end office calls the second terminal under the jurisdiction of the second telephone switching network end office, the softswitch device obtains the current first circuit state information of the first relay gateway.

Step 102a: The softswitch device selects the first relay gateway as the relay gateway for carrying the call between the first terminal and the second terminal according to the current first circuit state information.

FIG. 1B is a flowchart of another call routing method according to Embodiment 1 of the present invention. As shown in FIG. 1B , the call routing method includes:

Step 101b: When the first terminal under the jurisdiction of the first telephone switching network end office calls the second terminal under the jurisdiction of the second telephone switching network end office, the softswitch device obtains the current second circuit status information of the second trunk gateway.

Step 102b: The softswitch device selects the second relay gateway as the relay gateway for carrying the call between the first terminal and the second terminal according to the current second circuit state information.

FIG. 1C is a flowchart of another call routing method provided in Embodiment 1 of the present invention. As shown in FIG. 1C , the call routing method includes:

Step 101c: When the first terminal under the jurisdiction of the first telephone switching network end office calls the second terminal under the jurisdiction of the second telephone switching network end office, the softswitch device obtains the current third circuit status information of the first relay gateway.

Step 102c, the softswitch device acquires the current fourth circuit state information of the second relay gateway.

Step 103c, according to the current third circuit state information and the current fourth circuit state information, the softswitch device selects the first relay gateway and the second relay gateway as the relay gateways that carry the call between the first terminal and the second terminal .

In the technical solution of the call routing method provided in this embodiment, the first telephone switching network end office and the second telephone switching network end office are connected to the first trunk gateway and the second trunk gateway through different circuits, and when the When a user under the end office of a telephone switching network and a user under the end office of the second telephone switching network make a call, the softswitch device selects the first trunk gateway as the carrier of the first terminal and the second terminal according to the current first circuit state information The relay gateway for the call between the two, or the softswitch device selects the second relay gateway as the relay gateway to carry the call between the first terminal and the second terminal according to the current second circuit state information, or the softswitch The device selects the first relay gateway and the second relay gateway as the relay gateways carrying the call between the first terminal and the second terminal according to the current third circuit state information and the current fourth circuit state information. This effectively avoids the phenomenon that users under the PSTN end office cannot make or receive calls when the relay gateway fails, improving user experience.

FIG. 2 is a flowchart of a call routing method according to Embodiment 2 of the present invention. As shown in FIG. 2 , the call routing method includes:

Step 201: The first terminal sends a call request to the end office of the first telephone switching network to which it belongs, where the call request includes the number of the second terminal.

In this embodiment, the first terminal is used as the calling terminal, the number of the second terminal is the terminal number of the second terminal, and the second terminal is used as the called terminal. For example, the first terminal and the second terminal may be terminals such as a telephone landline or a mobile phone. , the first terminal number and the second terminal number may be telephone landline numbers or mobile phone numbers, etc., and the first terminal number is the terminal number of the first terminal.

In this embodiment, the first switched telephone network end office is a public switched telephone network (Public Switched Telephone Network, PSTN for short) end office to which the first terminal belongs.

Step 202, the first telephone switching network end office sends the initial address message and the second terminal number to the softswitch device.

Specifically, after the first terminal under the first telephone switching network end office goes off-hook and dials the second terminal number, the first telephone switching network end office sends the initial address message IAM and the second terminal number to the softswitch device.

Step 203: The softswitch device returns an address full message to the first telephone switching network end office.

Specifically, after the softswitch device receives the call request from the first telephone switching network end office, when it confirms that the second terminal number is complete and belongs to the user terminal number under the jurisdiction of the softswitch device, it returns to the first telephone switching network end office. Address full message.

Step 204: The softswitch device queries whether the end office of the first telephone switching network has access to the first relay gateway and the second relay gateway, and inquires whether the end office of the second telephone switching network has access to the first relay gateway and the second relay gateway. For the two relay gateways, if the query is yes, step 205 is performed; otherwise, a normal call flow is performed subsequently.

The second telephone switched network end office is a public switched telephone network (PSTN) end office to which the second terminal belongs.

Specifically, the softswitch device analyzes the number of the first terminal, and inquires out from the database the end office of the first telephone switching network, the first trunk gateway (TG for short) and the second middle office to which the first terminal number belongs. The corresponding relationship of the relay gateway (TG) is used to determine whether the end office of the first telephone switching network has access to the first relay gateway and the second relay gateway. Specifically, when the first telephone switching network end office corresponds to the first relay gateway and the second relay gateway in the database, it is determined that the first telephone switching network end office has access to the first relay gateway and the second relay gateway. Relay gateway, otherwise, the first telephone switching network end office does not access the first relay gateway and the second relay gateway, or the first telephone switching network end office only accesses the first relay gateway but not the second relay gateway. The relay gateway, or the first telephone switched network end office only accesses the second relay gateway and does not access the first relay gateway.

Similarly, the softswitch device analyzes the second terminal number, and queries the database for the correspondence between the second telephone switching network end office to which the second terminal number belongs, the first trunk gateway and the second trunk gateway, so as to determine Find out whether the end office of the second telephone switching network has access to the first trunk gateway and the second trunk gateway. Specifically, when the second telephone switching network end office in the database corresponds to the first relay gateway and the second relay gateway, it is determined that the second telephone switching network end office has access to the first relay gateway and the second relay gateway. Relay gateway, otherwise, the second telephone switching network end office does not access the first relay gateway and the second relay gateway, or the second telephone switching network end office only accesses the first relay gateway but not the second relay gateway. The relay gateway, or the second telephone switching network end office only accesses the second relay gateway and does not access the first relay gateway.

If the softswitch device finds that both the first telephone switching network end office and the second telephone switching network end office correspond to the first trunk gateway and the second trunk gateway, step 205 is performed; otherwise, the subsequent normal call flow is performed That's it.

Step 205: The softswitch device sends a first idle circuit query request to the first relay gateway.

Step 206: According to the first idle circuit query request, the first relay gateway determines whether the state of the circuit connected to the end office of the first telephone switching network is idle and whether the state of the circuit connected to the end office of the second telephone switching network is idle status, if both are judged to be yes, go to step 207; otherwise, go to step 209.

In this embodiment, the first telephone switching network end office is connected to the first relay gateway and the second relay gateway through different circuits, and the second telephone switching network end office is connected to the first relay gateway and the second relay gateway through different circuits Follow the gateway.

When there is an idle circuit between the first trunk gateway and the end office of the first telephone switching network, and there is an idle circuit between the first trunk gateway and the end office of the second telephone switching network, this call can pass through the first The relay gateway carries out the call between the users under the administration of the end office of the first telephone exchange network and the users under the administration of the end office of the second telephony exchange network.

When there is no idle circuit between the first trunk gateway and the first telephone switching network end office, and there is no idle circuit between the first trunk gateway and the second telephone switching network end office, that is, the first trunk gateway The circuits between the first telephone exchange network end office and the second telephone exchange network end office are in a busy state, so this call will temporarily not be able to carry the users under the first telephone exchange network end office through the first trunk gateway. Calls between users under the jurisdiction of the second telephone exchange network end office.

Step 207: The first relay gateway returns the current first circuit state information to the softswitch device, where the current first circuit state information includes the information used to determine that the first relay gateway accesses the first telephone switching network end office and the second telephone switching network The circuit state of the end office is all information of the idle state.

Step 208: The softswitch device selects the first relay gateway as the relay gateway for carrying the call between the first terminal and the second terminal according to the current first circuit state information of the first relay gateway, and ends the process.

Specifically, step 208 includes:

Step 2081: The softswitch device issues an add calling media command to the first relay gateway according to the current first circuit state information of the first relay gateway.

Wherein, in the command of adding the calling media, the extension information is added, and the extension information specifies that the type of the current call is a call within the same trunk gateway.

Step 2082: The first relay gateway applies for the calling circuit time slot and the calling medium to the first telephone switching network end office according to the adding calling medium command, and returns the application success information and the calling medium to the softswitch after the application is successful. media descriptor.

Specifically, the first relay gateway applies for the calling circuit time slot and the calling medium to the first telephone switching network end office according to the adding calling media command, but does not establish a temporary termination point (Termination), and after the application is successful, sends a The softswitch device returns the application success information and the calling media descriptor.

Step 2083: The softswitch device issues an add called media command to the first relay gateway according to the current first circuit state information of the first relay gateway.

Wherein, in the command for adding called media, extension information is added, and the extension information specifies that the type of this call is a call within the same trunk gateway. At the same time, the add called media command includes the calling media descriptor.

Step 2084: The first relay gateway applies for the called circuit time slot and the called medium to the second telephone switching network end office according to the command to add the called medium, and returns the application success information and the called medium to the softswitch after the application is successful. media descriptor.

Specifically, the first relay gateway applies for the called circuit time slot and the called medium to the second telephone switching network end office according to the command of adding the called medium, but does not establish a temporary termination point (Termination), and after the application is successful, sends a The softswitch device returns the application success information and the called media descriptor.

Step 2085: The first relay gateway establishes an association relationship between the calling media descriptor and the called media descriptor, and connects the calling and called media through the circuit-switched network.

Specifically, the first relay gateway establishes an association relationship between the calling media description and the called media description, and connects the calling and called media through the circuit-switched network to realize the call between the first terminal and the second terminal .

Step 209 , the first relay gateway returns the information that it does not have simultaneous connection capability and the current third circuit state information to the softswitch device.

Wherein, the information that the first relay gateway does not have simultaneous connection capability is used to indicate that at least one of the circuit status of the first relay gateway accessing the end office of the first telephone switching network and the circuit status of accessing the end office of the second telephone switching network Information that a circuit state is a non-idle state.

Specifically, if the first relay gateway determines that the state of the circuit connected to the end office of the first telephone switching network is in the idle state and the state of the circuit connected to the end office of the second telephone switching network is the non-idle state, the current third circuit state The information includes information for determining that the circuit state of the first relay gateway accessing the end office of the first telephone switching network is an idle state.

If the first trunk gateway determines that the state of the circuit connected to the end office of the first telephone switching network is in the non-idle state and the state of the circuit connected to the end office of the second telephone switching network is the idle state, the current third circuit state information includes: Information for determining that the circuit state of the end office of the first relay gateway accessing the second telephone switching network is the idle state.

If the first relay gateway determines that the state of the circuit connected to the end office of the first telephone switching network is in the non-idle state and the state of the circuit connected to the end office of the second telephone switching network is the non-idle state, the current third circuit state information includes: Information used to determine whether the circuit state of the first relay gateway accessing the end office of the first telephone switching network is a non-idle state and the circuit state of accessing the end office of the second telephone switching network is a non-idle state.

Step 210: The softswitch device sends a second idle circuit query request to the second relay gateway according to the information of the first relay gateway not having simultaneous connection capability.

Step 211: According to the second idle circuit query request, the second relay gateway determines whether the state of the circuit connected to the end office of the first telephone switching network is idle and whether the state of the circuit connected to the end office of the second telephone switching network is idle status, if both are determined to be yes, go to step 212; otherwise, go to step 214.

When there is an idle circuit between the second trunk gateway and the end office of the first telephone switching network, and there is an idle circuit between the second trunk gateway and the end office of the second telephone switching network, the current call can pass through the second telephone switching network. The relay gateway carries out the call between the users under the administration of the end office of the first telephone exchange network and the users under the administration of the end office of the second telephony exchange network.

When there is no idle circuit between the second trunk gateway and the first telephone switching network end office, and there is no idle circuit between the second trunk gateway and the second telephone switching network end office, that is, the second trunk gateway The circuits between the first and second TSN end offices are in a busy state, so this call will temporarily not be able to carry users under the first TSN end office through the second trunk gateway. Calls between users under the jurisdiction of the second telephone exchange network end office.

When there is an idle circuit between the first trunk gateway and the end office of the first telephone switching network, and there is an idle circuit between the second trunk gateway and the end office of the second telephone switching network, this call can pass through the first The relay gateway and the second relay gateway carry out a call between a user under the end office of the first telephone switching network and a user under the end office of the second telephone switching network.

When there is an idle circuit between the second trunk gateway and the end office of the first telephone switching network, and there is an idle circuit between the first trunk gateway and the end office of the second telephone switching network, the call can pass through the first The relay gateway and the second relay gateway carry out a call between a user under the end office of the first telephone switching network and a user under the end office of the second telephone switching network.

Step 212, the second relay gateway returns the current second circuit status information to the softswitch device, where the current second circuit status information includes the information used to determine that the second relay gateway accesses the first telephone switching network end office and the second telephone switching network The circuit state of the end office is all information of the idle state.

Step 213: The softswitch device selects the second relay gateway as the relay gateway for carrying the call between the first terminal and the second terminal according to the current second circuit state information of the second relay gateway, and ends the process.

Specifically, step 213 includes:

Step 2131: The softswitch device issues an add calling media command to the second relay gateway according to the current second circuit state information of the second relay gateway.

Wherein, in the command of adding the calling media, the extension information is added, and the extension information specifies that the type of the current call is a call within the same trunk gateway.

Step 2132, the second trunk gateway applies for the calling circuit time slot and the calling medium to the first telephone switching network end office according to the adding calling medium command, and after the application is successful, returns the application success information and the calling medium to the softswitch device. media descriptor.

Specifically, the second relay gateway applies for the calling circuit time slot and the calling medium from the first telephone switching network end office according to the adding calling media command, but does not establish a temporary termination point (Termination), and after the application is successful, sends a The softswitch device returns the application success information and the calling media descriptor.

Step 2133: The softswitch device issues an add called media command to the second relay gateway according to the current second circuit state information of the second relay gateway.

Wherein, in the command for adding called media, extension information is added, and the extension information specifies that the type of this call is a call within the same trunk gateway. At the same time, the add called media command includes the calling media descriptor.

Step 2134: The second relay gateway applies for the called circuit time slot and the called medium to the second telephone switching network end office according to the command to add the called medium, and returns the application success information and the called medium to the softswitch after the application is successful. media descriptor.

Specifically, the second relay gateway applies for the called circuit time slot and the called medium to the second telephone switching network end office according to the command to add the called medium, but does not establish a temporary termination point (Termination), and after the application is successful, sends a The softswitch device returns the application success information and the called media descriptor.

Step 2135: The second relay gateway establishes an association relationship between the calling media descriptor and the called media descriptor, and connects the calling and called media through the circuit-switched network.

Specifically, the second relay gateway establishes an association relationship between the calling media description and the called media description, and connects the calling and called media through the circuit-switched network to realize the call between the first terminal and the second terminal .

Step 214 , the second relay gateway returns the information of not having simultaneous connection capability and the current fourth circuit state information to the softswitch device.

Wherein, the information that the second relay gateway does not have simultaneous connection capability is used to indicate that at least one of the circuit status of the second relay gateway accessing the end office of the first telephone switching network and the circuit status of accessing the end office of the second telephone switching network Information that a circuit state is a non-idle state.

Specifically, if the second relay gateway determines that the state of the circuit connected to the end office of the first telephone switching network is in the non-idle state and the state of the circuit connected to the end office of the second telephone switching network is the idle state, the current fourth circuit state The information includes information for determining that the circuit state of the second trunk gateway accessing the end office of the second telephone switching network is an idle state.

If the second trunk gateway determines that the state of the circuit connected to the end office of the first telephone switching network is in the idle state and the state of the circuit connected to the end office of the second telephone switching network is the non-idle state, the current fourth circuit state information includes Information for determining that the circuit state of the end office of the second trunk gateway accessing the first telephone switching network is the idle state.

If the second trunk gateway determines that the state of the circuit connected to the end office of the first telephone switching network is in the non-idle state and the state of the circuit connected to the end office of the second telephone switching network is the non-idle state, the current fourth circuit state information includes: Information used to determine whether the circuit state of the second trunk gateway accessing the end office of the first telephone switching network is a non-idle state and the state of the circuit accessing the end office of the first telephone switching network is a non-idle state.

Step 215: The softswitch device selects the first relay gateway and the second relay gateway as the relay gateways that carry the call between the first terminal and the second terminal according to the current third circuit state information and the current fourth circuit state information , or, the softswitch device releases the current call according to the current third circuit state information and the current fourth circuit state information.

Specifically, if the current third circuit status information includes information used to determine that the circuit status of the first trunk gateway accessing the end office of the first telephone switching network is an idle state, the current fourth circuit status information includes information used to determine the second circuit status information. When the circuit status of the relay gateway accessing the second telephone switching network end office is idle, or if the current third circuit status information includes the circuit used to determine that the first relay gateway accesses the second telephone switching network end office The information that the state is the idle state, the current fourth circuit state information includes the information used to determine that the circuit state of the second trunk gateway accessing the end office of the first telephone switching network is the idle state, the softswitch device will be based on the current third circuit state. information and the current fourth circuit state information, select the first relay gateway and the second relay gateway as the relay gateways that carry the call between the first terminal and the second terminal.

If the current third circuit state information includes the information used to determine that the circuit state of the first trunk gateway accessing the end office of the first telephone switching network is in the non-idle state and the state of the circuit accessing the end office of the second telephone switching network is the non-idle state information, the current fourth circuit state information includes the state of the circuit used to determine that the second trunk gateway accesses the end office of the first telephone switching network is a non-idle state and the circuit state that accesses the end office of the first telephone switching network is a non-idle state information, the softswitch device releases the call according to the current third circuit state information and the current fourth circuit state information.

Specifically, if the current third circuit status information includes information used to determine that the circuit status of the first trunk gateway accessing the end office of the first telephone switching network is an idle state, the current fourth circuit status information includes information used to determine the second circuit status information. When the gateway accesses the information that the circuit state of the end office of the second telephone switching network is the idle state, step 215 includes:

Step 2151a, the softswitch device issues an add calling media command to the first relay gateway according to the current third circuit state information.

Wherein, in the command of adding calling media, extended information is added, and the extended information specifies that the type of this call is a call in a different trunk gateway.

Step 2152a, the first relay gateway applies for the calling circuit time slot and the calling medium to the first telephone switching network end office according to the adding calling medium command, and after the application is successful, returns the application success information and the calling medium to the softswitch device. media descriptor.

Specifically, the first relay gateway applies for the calling circuit time slot and the calling medium from the first telephone switching network end office according to the adding calling media command, establishes a temporary termination point (Termination), and sends a The switching device returns the application success information and the calling media descriptor.

Step 2153a: The softswitch device issues an add called media command to the second relay gateway according to the current fourth circuit state information.

Wherein, in the command for adding called media, extension information is added, and the extension information specifies that the type of the current call is a call in a different trunk gateway. At the same time, the add called media command includes the calling media descriptor.

Step 2154a, the second relay gateway applies for the called circuit time slot and the called medium to the second telephone switching network end office according to the command of adding the called medium, and after the application is successful, returns the application success information and the called medium to the softswitch device. media descriptor.

Specifically, the second relay gateway applies for the called circuit time slot and the called medium to the second telephone switching network end office according to the command to add the called medium, establishes a temporary termination point (Termination), and sends a The switching device returns the application success information and the called media descriptor.

In step 2155a, the first relay gateway and the second relay gateway respectively establish an association relationship between the calling media descriptor and the called media descriptor, and connect the calling and called media through the circuit switching network.

Specifically, the first relay gateway and the second relay gateway respectively establish an association relationship between the calling media descriptor and the called media descriptor, and connect the calling and called media through the circuit switching network to realize the first terminal call with the second terminal.

If the current third circuit status information includes information used to determine that the circuit status of the first trunk gateway accessing the end office of the second telephone switching network is an idle state, the current fourth circuit status information includes information used to determine that the second trunk gateway is connected to When entering the information that the circuit state of the first telephone switching network end office is an idle state, step 215 includes:

Step 2151b, the softswitch device issues an add calling media command to the second relay gateway according to the current fourth circuit state information.

Wherein, in the command of adding calling media, extended information is added, and the extended information specifies that the type of this call is a call in a different trunk gateway.

Step 2152b, the second trunk gateway applies for the calling circuit time slot and the calling medium to the first telephone switching network end office according to the adding calling medium command, and returns the application success information and the calling medium to the softswitch after the application is successful. media descriptor.

Specifically, the second relay gateway applies for the calling circuit time slot and the calling medium from the first telephone switching network end office according to the adding calling media command, and establishes a temporary termination point (Termination). The switching device returns the application success information and the calling media descriptor.

Step 2153b: The softswitch device issues an add called media command to the first relay gateway according to the current third circuit state information.

Wherein, in the command for adding called media, extension information is added, and the extension information specifies that the type of the current call is a call in a different trunk gateway. At the same time, the add called media command includes the calling media descriptor.

Step 2154b, the first relay gateway applies for the called circuit time slot and the called medium to the second telephone switching network end office according to the command of adding the called medium, and returns the application success information and the called medium to the softswitch after the application is successful. media descriptor.

Specifically, the first relay gateway applies for the called circuit time slot and the called medium to the end office of the second telephone switching network according to the add called media command, establishes a temporary termination point (Termination), and sends a The switching device returns the application success information and the called media descriptor.

In step 2155b, the first relay gateway and the second relay gateway respectively establish an association relationship between the calling media descriptor and the called media descriptor, and connect the calling and called media through the circuit switching network.

Specifically, the first relay gateway and the second relay gateway respectively establish an association relationship between the calling media descriptor and the called media descriptor, and connect the calling and called media through the circuit switching network to realize the first terminal call with the second terminal.

In this embodiment, the end office of the first switched telephone network and the end office of the second switched telephone network are connected to the first trunk gateway and the second trunk gateway through different circuits. When a user under the end office of the second telephone switching network makes a call, the softswitch device selects the first relay gateway as the relay gateway to carry the call between the first terminal and the second terminal according to the current first circuit state information, or , the softswitch device selects the second relay gateway as the relay gateway to carry the call between the first terminal and the second terminal according to the current second circuit state information, or the softswitch device selects the second relay gateway according to the current third circuit state information and the current In the fourth circuit state information, the first relay gateway and the second relay gateway are selected as relay gateways for carrying the call between the first terminal and the second terminal. This effectively avoids the phenomenon that users under the PSTN end office cannot make or receive calls when the relay gateway fails, and improves user experience.

In this embodiment, when a user under the end office of the first telephone switching network and a user under the end office of the second telephone switching network make a call, before the call routing is selected, the first relay gateway and the first telephone exchange are firstly performed. The circuit status between the network end offices and the circuit status with the first telephone switching network end office are judged. When there is an idle circuit between the first relay gateway and the first telephone switching network end office, the first relay When there is an idle circuit between the gateway and the second telephone switching network end office, the first relay gateway is selected according to the current first circuit state information to carry the users under the first telephone switching network end office and the second telephone switching network terminal. Calls between users under the jurisdiction of the bureau. When the first trunk gateway does not have the simultaneous connection capability, further judge the circuit state between the second trunk gateway and the first telephone switching network end office and the circuit status between the second trunking gateway and the first telephone switching network end office, When there is an idle circuit between the second trunk gateway and the first telephone switching network end office, and there is an idle circuit between the second trunk gateway and the second telephone switching network end office, according to the current second circuit state information The second relay gateway is selected to carry the call between the user under the jurisdiction of the first telephone switching network end office and the user under the second telephone switching network end office. In this way, since only the first relay gateway or the second relay gateway is selected for bearer calls, there is no need to establish an RTP media stream between the first relay gateway and the second relay gateway, so that the selection of the first relay gateway can be avoided. The phenomenon of wasting the media resources of the relay gateway and consuming the resources of the bearer network when the call is jointly carried with the second relay gateway.

Only when the first relay gateway does not have the simultaneous connection capability and the second relay gateway does not have the simultaneous connection capability, select the first relay gateway and the second relay gateway according to the current third circuit state information and the current fourth circuit state information Carry out the bearer call on the relay gateway or release the call.

In the technical solution of the call routing method provided in this embodiment, the first telephone switching network end office and the second telephone switching network end office are connected to the first trunk gateway and the second trunk gateway through different circuits, and when the When a user under the end office of a telephone switching network and a user under the end office of the second telephone switching network make a call, the softswitch device selects the first trunk gateway as the carrier of the first terminal and the second terminal according to the current first circuit state information The relay gateway for the call between the two, or the softswitch device selects the second relay gateway as the relay gateway to carry the call between the first terminal and the second terminal according to the current second circuit state information, or the softswitch The device selects the first relay gateway and the second relay gateway as the relay gateways carrying the call between the first terminal and the second terminal according to the current third circuit state information and the current fourth circuit state information. This effectively avoids the phenomenon that users under the PSTN end office cannot make or receive calls when the relay gateway fails, improving user experience.

FIG. 3 is a schematic structural diagram of a call routing system according to Embodiment 3 of the present invention. As shown in FIG. 3 , the call routing system includes a softswitch device 301 , a first telephone switching network end office 302 , and a first terminal 303 , the second telephone switching network end office 304 , the second terminal 305 , the first relay gateway 306 and the second relay gateway 307 .

The softswitch device 301 is used to obtain the current first circuit of the first relay gateway 306 when the first terminal 303 under the jurisdiction of the first telephone switching network end office 302 calls the second terminal 305 under the jurisdiction of the second telephone switching network end office 304 Status information; according to the current first circuit status information, select the first relay gateway 305 as the relay gateway to carry the call between the first terminal 303 and the second terminal 305; or,

The softswitch device 301 is used to obtain the current second circuit of the second trunk gateway 307 when the first terminal 303 under the jurisdiction of the first switched telephone network end office 302 calls the second terminal 305 under the jurisdiction of the second telephone exchange network end office 304 Status information; according to the current second circuit status information, select the second relay gateway 307 as the relay gateway to carry the call between the first terminal 303 and the second terminal 305; or,

The softswitch device 301 is used to obtain the current third circuit of the first relay gateway 306 when the first terminal 303 of the first switched telephone network end office 302 calls the second terminal 305 of the second telephone switched network end office 304 state information; obtain the current fourth circuit state information of the second relay gateway 307; according to the current third circuit state information and the current fourth circuit state information, select the first relay gateway 306 and the second relay gateway 307 as the carrier A relay gateway for calls between a terminal 303 and a second terminal 305 .

Specifically, the current first circuit state information includes information for determining that the circuit states of the first trunk gateway 306 accessing the first telephone switching network end office 302 and the second telephone switching network end office 304 are both idle states. The softswitch device 301 is further configured to send a first idle circuit query request to the first relay gateway 306 . The first relay gateway 306 is configured to, according to the first idle circuit query request, determine whether the state of the circuit connected to the end office 302 of the first telephone switching network is an idle state and whether the state of the circuit connected to the end office 304 of the second telephone switching network is in an idle state. If it is judged that the state of the circuit connected to the end office 302 of the first telephone switching network is in the idle state and the state of the circuit connected to the end office 304 of the second telephone switching network is the idle state, it will return to the softswitch device 301 the current first a circuit status information.

Specifically, the current second circuit state information includes information for determining that the circuit states of the second trunk gateway 307 accessing the first telephone switching network end office 302 and the second telephone switching network end office 304 are both idle states. The first relay gateway 306 is also configured to determine that at least one of the circuit states accessing the first telephone switching network end office 302 and the circuit status accessing the second telephone switching network end office 304 is a non-idle state, Return to the softswitch device 301 no simultaneous connection capability information. The softswitch device 301 is further configured to send a second idle circuit query request to the second relay gateway 307 according to the information of the first relay gateway 306 not having simultaneous connection capability. The second relay gateway 307 is configured to judge whether the state of the circuit connected to the end office 302 of the first telephone switching network is an idle state and whether the state of the circuit connected to the end office 304 of the second telephone switching network is in an idle state according to the second idle circuit query request It is an idle state; if it is determined that the state of the circuit connected to the end office 302 of the first telephone switching network is idle and the state of the circuit that is connected to the end office 304 of the second telephone switching network is idle, it will send the current No. 2. Circuit status information.

Optionally, the current third circuit state information includes information used to determine that the circuit state of the first trunk gateway 306 accessing the first telephone switching network end office 302 is an idle state, and the current fourth circuit state information includes information used to determine the first circuit state. The second relay gateway 307 accesses the information that the circuit state of the second telephone switching network end office 304 is the idle state. The first relay gateway 306 is also specifically configured to, if it is judged that the state of the circuit connected to the end office 302 of the first telephone switching network is in an idle state and the state of the circuit connected to the end office 304 of the second telephone switching network is a non-idle state, to send the The softswitch device 301 sends the current third circuit state information. The second relay gateway 307 is also specifically configured to, if it is determined that the state of the circuit connected to the end office 302 of the first telephone switching network is in the non-idle state and the state of the circuit connected to the end office 304 of the second telephone switching network is the idle state, to send the The softswitch device 301 sends the current fourth circuit state information.

Optionally, the current third circuit state information includes information used to determine that the circuit state in which the first trunk gateway 306 accesses the second telephone switching network end office 304 is an idle state, and the current fourth circuit state information includes information used to determine the first circuit state. The second relay gateway 307 accesses the information that the circuit state of the first telephone switching network end office 302 is the idle state. The first relay gateway 306 is also specifically configured to, if it is determined that the state of the circuit connected to the end office 302 of the first telephone switching network is in the non-idle state and the state of the circuit connected to the end office 304 of the second telephone switching network is the idle state, to send the The softswitch device 301 sends the current third circuit state information. The second relay gateway 307 is also specifically configured to, if it is determined that the state of the circuit connected to the end office 302 of the first telephone switching network is in an idle state and the state of the circuit connected to the end office 304 of the second telephone switching network is a non-idle state, send the The softswitch device 301 sends the current fourth circuit state information.

The call routing system provided in this embodiment is used to implement the call routing method provided in the second embodiment. For a specific description, refer to the second embodiment, which will not be repeated here.

In the technical solution of the call routing system provided by this embodiment, the end office of the first telephone switching network and the end office of the second telephone switching network are connected to the first trunk gateway and the second trunk gateway through different circuits. When a user under the end office of a telephone switching network and a user under the end office of the second telephone switching network make a call, the softswitch device selects the first trunk gateway as the carrier of the first terminal and the second terminal according to the current first circuit state information The relay gateway for the call between the two, or the softswitch device selects the second relay gateway as the relay gateway to carry the call between the first terminal and the second terminal according to the current second circuit state information, or the softswitch The device selects the first relay gateway and the second relay gateway as the relay gateways carrying the call between the first terminal and the second terminal according to the current third circuit state information and the current fourth circuit state information. This effectively avoids the phenomenon that users under the PSTN end office cannot make or receive calls when the relay gateway fails, improving user experience.

It can be understood that the above embodiments are only exemplary embodiments adopted to illustrate the principle of the present invention, but the present invention is not limited thereto. For those skilled in the art, without departing from the spirit and essence of the present invention, various modifications and improvements can be made, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims (10)

1. A method for call routing, comprising:

when a first terminal under the jurisdiction of a first telephone switching network end office calls a second terminal under the jurisdiction of a second telephone switching network end office, the soft switch equipment acquires the current first circuit state information of a first relay gateway;

the soft switch equipment selects a first relay gateway as a relay gateway for bearing the conversation between the first terminal and the second terminal according to the current first circuit state information; or,

when a first terminal under the jurisdiction of a first telephone switching network end office calls a second terminal under the jurisdiction of a second telephone switching network end office, the soft switch equipment acquires the current second circuit state information of a second relay gateway;

the soft switch equipment selects a second relay gateway as a relay gateway for bearing the call between the first terminal and the second terminal according to the current second circuit state information; or,

when a first terminal administered by a first telephone switching network end office calls a second terminal administered by a second telephone switching network end office, the soft switching equipment acquires the current third circuit state information of the first relay gateway;

the soft switch equipment acquires the current fourth circuit state information of the second relay gateway;

and the soft switch equipment selects the first relay gateway and the second relay gateway as the relay gateway for bearing the call between the first terminal and the second terminal according to the current third circuit state information and the current fourth circuit state information.

2. The call routing method according to claim 1, wherein the current first circuit state information includes information for determining that the circuit states of the first trunking gateway accessing the first telephone switching network end office and the second telephone switching network end office are idle states, and the method for the softswitch device to obtain the current first circuit state information of the first trunking gateway further includes:

the soft switch equipment sends a first idle circuit query request to a first relay gateway;

the first relay gateway judges whether the circuit state accessed to the first telephone exchange network end office is an idle state or not and judges whether the circuit state accessed to the second telephone exchange network end office is an idle state or not according to the first idle circuit inquiry request;

and if the first relay gateway judges that the circuit state accessed to the first telephone exchange network end office is an idle state and the circuit state accessed to the second telephone exchange network end office is an idle state, returning the current first circuit state information to the soft switch equipment.

3. The call routing method according to claim 1, wherein the current second circuit state information includes information for determining that the circuit states of the second trunking gateway accessing the first telephone switching network end office and the second telephone switching network end office are idle states, and the method for the softswitch device to obtain the current second circuit state information of the second trunking gateway further includes:

the soft switch equipment sends a first idle circuit query request to a first relay gateway;

the first relay gateway judges whether the circuit state accessed to the first telephone exchange network end office is an idle state or not and judges whether the circuit state accessed to the second telephone exchange network end office is an idle state or not according to the first idle circuit inquiry request;

if the first relay gateway judges that at least one circuit state of the circuit state accessed to the first telephone exchange network end office and the circuit state accessed to the second telephone exchange network end office is a non-idle state, returning information without simultaneous connection capability to the soft switch equipment;

the soft switch equipment sends a second idle circuit query request to a second relay gateway according to the information that the first relay gateway does not have the simultaneous connection capability;

the second relay gateway judges whether the circuit state accessed to the first telephone exchange network end office is an idle state or not and judges whether the circuit state accessed to the second telephone exchange network end office is an idle state or not according to the second idle circuit inquiry request;

and if the second relay gateway judges that the circuit state accessed to the first telephone exchange network end office is an idle state and the circuit state accessed to the second telephone exchange network end office is an idle state, the second relay gateway sends the current second circuit state information to the soft switch equipment.

4. The call routing method according to claim 1, wherein the current third circuit state information includes information for determining that a circuit state of the first trunking gateway accessing the first telephone switching network end office is an idle state, and the current fourth circuit state information includes information for determining that a circuit state of the second trunking gateway accessing the second telephone switching network end office is an idle state;

before the soft switch device obtains the current third circuit state information of the first relay gateway, the method further includes:

the soft switch equipment sends a first idle circuit query request to a first relay gateway;

the first relay gateway judges whether the circuit state accessed to the first telephone exchange network end office is an idle state or not and judges whether the circuit state accessed to the second telephone exchange network end office is an idle state or not according to the first idle circuit inquiry request;

if the first relay gateway judges that the circuit state accessed to the first telephone exchange network end office is an idle state and the circuit state accessed to the second telephone exchange network end office is a non-idle state, the first relay gateway sends the current third circuit state information to the soft switch equipment;

before the soft switch device obtains the current fourth circuit state information of the second relay gateway, the method further includes:

the soft switch equipment sends a second idle circuit query request to a second relay gateway;

the second relay gateway judges whether the circuit state accessed to the first telephone exchange network end office is an idle state or not and judges whether the circuit state accessed to the second telephone exchange network end office is an idle state or not according to the second idle circuit inquiry request;

and if the second relay gateway judges that the circuit state accessed to the first telephone exchange network end office is a non-idle state and the circuit state accessed to the second telephone exchange network end office is an idle state, the second relay gateway sends the current fourth circuit state information to the soft switch equipment.

5. The call routing method according to claim 1, wherein the current third circuit state information includes information for determining that a circuit state of the first trunking gateway accessing the second telephone switching network end office is an idle state, and the current fourth circuit state information includes information for determining that a circuit state of the second trunking gateway accessing the first telephone switching network end office is an idle state;

before the soft switch device obtains the current third circuit state information of the first relay gateway, the method further includes:

the soft switch equipment sends a first idle circuit query request to a first relay gateway;

the first relay gateway judges whether the circuit state accessed to the first telephone exchange network end office is an idle state or not and judges whether the circuit state accessed to the second telephone exchange network end office is an idle state or not according to the first idle circuit inquiry request;

if the first relay gateway judges that the circuit state accessed to the first telephone exchange network end office is a non-idle state and the circuit state accessed to the second telephone exchange network end office is an idle state, the first relay gateway sends the current third circuit state information to the soft switch equipment;

before the soft switch device obtains the current fourth circuit state information of the second relay gateway, the method further includes:

the soft switch equipment sends a second idle circuit query request to a second relay gateway;

the second relay gateway judges whether the circuit state accessed to the first telephone exchange network end office is an idle state or not and judges whether the circuit state accessed to the second telephone exchange network end office is an idle state or not according to the second idle circuit inquiry request;

and if the second relay gateway judges that the circuit state accessed to the first telephone exchange network end office is an idle state and the circuit state accessed to the second telephone exchange network end office is a non-idle state, the second relay gateway sends the current fourth circuit state information to the soft switch equipment.

6. A call routing system is characterized by comprising a soft switch device, a first telephone switching network end office, a first terminal, a second telephone switching network end office, a second terminal, a first relay gateway and a second relay gateway;

the soft switch equipment is used for acquiring the current first circuit state information of the first relay gateway when a first terminal under the jurisdiction of a first telephone switching network end office calls a second terminal under the jurisdiction of a second telephone switching network end office; selecting a first relay gateway as a relay gateway for bearing the call between the first terminal and the second terminal according to the current first circuit state information; or,

the soft switch equipment is used for acquiring the current second circuit state information of the second relay gateway when a first terminal under the jurisdiction of the first telephone switching network end office calls a second terminal under the jurisdiction of the second telephone switching network end office; selecting a second relay gateway as a relay gateway for bearing the call between the first terminal and the second terminal according to the current second circuit state information; or,

the soft switch equipment is used for acquiring the current third circuit state information of the first relay gateway when a first terminal under the jurisdiction of a first telephone switching network end office calls a second terminal under the jurisdiction of a second telephone switching network end office; acquiring current fourth circuit state information of a second relay gateway; and selecting the first relay gateway and the second relay gateway as the relay gateway for bearing the call between the first terminal and the second terminal according to the current third circuit state information and the current fourth circuit state information.

7. The call routing system of claim 6, wherein the current first circuit state information includes information for determining that the circuit states of the first trunking gateway accessing the first and second telephone-switched network end offices are idle states;

the soft switch equipment is also used for sending a first idle circuit inquiry request to the first relay gateway;

the first relay gateway is used for judging whether the circuit state accessed to the first telephone exchange network end office is an idle state or not and judging whether the circuit state accessed to the second telephone exchange network end office is an idle state or not according to the first idle circuit inquiry request; and if the circuit state accessed to the first telephone exchange network end office is judged to be an idle state and the circuit state accessed to the second telephone exchange network end office is judged to be an idle state, returning the current first circuit state information to the soft switch equipment.

8. The call routing system of claim 6, wherein the current second circuit state information includes information for determining that the circuit states of the second trunking gateway accessing the first telephone-switched network end office and the second telephone-switched network end office are idle states;

the soft switch equipment is also used for sending a first idle circuit inquiry request to the first relay gateway;

the first relay gateway is used for judging whether the circuit state accessed to the first telephone exchange network end office is an idle state or not and judging whether the circuit state accessed to the second telephone exchange network end office is an idle state or not according to the first idle circuit inquiry request; if at least one circuit state of the circuit state accessed to the first telephone exchange network end office and the circuit state accessed to the second telephone exchange network end office is judged to be a non-idle state, returning information without simultaneous connection capability to the soft switch equipment;

the soft switch equipment is also used for sending a second idle circuit query request to a second relay gateway according to the information that the first relay gateway does not have the simultaneous connection capability;

the second relay gateway is used for judging whether the circuit state accessed to the first telephone exchange network end office is an idle state or not and judging whether the circuit state accessed to the second telephone exchange network end office is an idle state or not according to the second idle circuit inquiry request; and if the circuit state accessed to the first telephone exchange network end office is judged to be an idle state and the circuit state accessed to the second telephone exchange network end office is judged to be an idle state, the current second circuit state information is sent to the soft switch equipment.

9. The call routing system of claim 6, wherein the current third circuit state information includes information for determining that a circuit state of the first trunking gateway accessing the first telephone switching network end office is idle, and wherein the current fourth circuit state information includes information for determining that a circuit state of the second trunking gateway accessing the second telephone switching network end office is idle;

the soft switch equipment is also used for sending a first idle circuit inquiry request to the first relay gateway;

the first relay gateway is used for judging whether the circuit state accessed to the first telephone exchange network end office is an idle state or not and judging whether the circuit state accessed to the second telephone exchange network end office is an idle state or not according to the first idle circuit inquiry request; if the circuit state accessed to the first telephone exchange network end office is judged to be an idle state and the circuit state accessed to the second telephone exchange network end office is judged to be a non-idle state, the current third circuit state information is sent to the soft switch equipment;

the soft switch equipment is also used for sending a second idle circuit inquiry request to the second relay gateway;

the second relay gateway is used for judging whether the circuit state accessed to the first telephone exchange network end office is an idle state or not and judging whether the circuit state accessed to the second telephone exchange network end office is an idle state or not according to the second idle circuit inquiry request; and if the circuit state accessed to the first telephone exchange network end office is judged to be a non-idle state and the circuit state accessed to the second telephone exchange network end office is judged to be an idle state, the current fourth circuit state information is sent to the soft switch equipment.

10. The call routing system of claim 6, wherein the current third circuit state information includes information for determining that the circuit state of the first trunking gateway accessing the second telephone switching network end office is idle, and wherein the current fourth circuit state information includes information for determining that the circuit state of the second trunking gateway accessing the first telephone switching network end office is idle;

the soft switch equipment is also used for sending a first idle circuit inquiry request to the first relay gateway;

the first relay gateway is used for judging whether the circuit state accessed to the first telephone exchange network end office is an idle state or not and judging whether the circuit state accessed to the second telephone exchange network end office is an idle state or not according to the first idle circuit inquiry request; if the circuit state accessed to the first telephone exchange network end office is judged to be a non-idle state and the circuit state accessed to the second telephone exchange network end office is judged to be an idle state, the current third circuit state information is sent to the soft switch equipment;

the soft switch equipment is also used for sending a second idle circuit inquiry request to the second relay gateway;

the second relay gateway is used for judging whether the circuit state accessed to the first telephone exchange network end office is an idle state or not and judging whether the circuit state accessed to the second telephone exchange network end office is an idle state or not according to the second idle circuit inquiry request; and if the circuit state accessed to the first telephone exchange network end office is judged to be an idle state and the circuit state accessed to the second telephone exchange network end office is judged to be a non-idle state, the current fourth circuit state information is sent to the soft switch equipment.