CN1266901C - A call flow setting up method - Google Patents

Abstract

It relates to a method for establishing a call flow in the field of communication technology. Before a softswitch sends an initial address message (IAM) sent by a calling signaling gateway to a called signaling gateway, the calling trunk gateway has been controlled by a Modify request to obtain the It is called the IP address and port number of the RTP endpoint, so the trunk gateway has been controlled to complete the establishment of the media stream before the softswitch sends the IAM, so even if the called party picks up the phone immediately after ringing, there will be no media stream after picking up the phone The situation that has not been established yet; the present invention provides a more complete method for establishing a call flow.

Description

A method for establishing a call flow

technical field

The invention relates to the technical field of communication, in particular to a method for establishing a call flow.

Background technique

Softswitch is the control function entity of NGN (New Generation Network), which provides call control and connection control functions for services with real-time requirements for the next generation network, and is the core of call and control in the next generation network. Among them, the control is resolved through negotiation, and accordingly there must be an agreement. In the NGN architecture, the softswitch is the control center, which is realized by supporting multiple protocols such as H.248.

The H.248 protocol is a control protocol between the media gateway controller and the media gateway. It is a master-slave protocol, with the media gateway controller as the master and the media gateway as the slave. The media gateway controller controls various service gateways to realize For the intercommunication between the packet network and the public switched telephone network (PSTN), at present, international and domestic standard organizations have made relevant suggestions on the call establishment process related to the H.248 protocol.

Termination is a logical entity on a media gateway (MG: Media Gateway), which initiates and/or receives media and/or control streams, TDM termination is a semi-permanent termination, RTP termination is a temporary termination point. Context indicates the connection relationship between endpoints. It can be created by Add command, modified by Modify command, or deleted by Subtract and Move commands. An endpoint belongs to and can only belong to one association at any time.

As shown in Figure 1, the existing call establishment process initiated by a trunk media gateway (TMG: Trunk Media Gateway), the trunk media gateway is connected to the user through the circuit relay in the circuit switched network, and the call signaling is determined by the signaling The gateway (SG: Signaling Gateway) enters the softswitch device through SS7, and agrees:

(1) The calling user is located in the jurisdiction of the trunk media gateway TMG1 and the signaling gateway SG1;

(2) The called user is located in the jurisdiction of the trunk media gateway TMG2 and the signaling gateway SG2;

(3) The trunk media gateways TMG1 and TMG2 belong to the jurisdiction of a softswitch;

(4) SS7 adopts ISUP signaling;

ISUP protocol messages include: initial address message IAM (Initial Address Message), address complete message ACM (Address Completion Message), answer message ANM (AnswerMessage), etc.

The existing call flow is as follows:

(1) After the user dials, send (IAM) to the softswitch through the calling SS7 gateway.

(2) Create a new association (Context) in TMG1, and add a semi-permanent termination point (TDM) and a temporary termination point (RTP) in the association.

(3) Create a new association in TMG2, and add a semi-permanent termination point (TDM) and a temporary termination point (RTP) in the association.

(4) The soft switch sends an IAM to the circuit switching network through the called SS7 gateway, and the circuit switching network sends an ACM back, and the called party rings.

(5) The softswitch sends a Modify command to TMG1 to inform the remote RTP port number and IP address, and to send a ringback tone.

(6) The softswitch sends the ACM to SG1.

(7) The called party picks up the hook, and SG2 sends ANM to the softswitch.

(8) The soft switch sends a Modify command to TMG1 to cut off the ring back tone.

(9) The soft switch sends ANM to SG1.

Based on the above process, there is a problem in the implementation: if the called party picks up the phone immediately after ringing, it will be found that the media stream has not been established. It can also be seen from Figure 1 that the called SS7 gateway sends the IAM sent by the softswitch. To the circuit switching network, the circuit switching network returns the ACM, and the called party rings, but the softswitch receives the ACM sent back by the circuit switching network through the called SS7 signaling gateway, and then controls the calling trunk gateway to obtain the called RTP through the Modify request The IP address and port number of the endpoint, and then the relay gateway completes the establishment of the media stream. There is a certain delay, so the media stream will not be established when the phone is picked up immediately.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the defects of the existing call flow, and provide a method for establishing a call flow that has already established a media stream when the called party picks up the phone immediately after ringing.

The technical scheme that the present invention adopts for solving the above-mentioned technical problem is: the establishment method of this call flow, comprises the following steps:

A. The user dials, and sends an initial address message to the softswitch through the calling SS7 gateway;

B. Create a new association in the calling trunk media gateway, and add a semi-permanent termination point and a temporary termination point to the association;

C. Create a new association in the called trunk media gateway, and add a semi-permanent termination point and a temporary termination point to the association;

D. The soft switch sends a Modify command to the calling trunk media gateway, and informs the port number and IP address of the remote temporary termination point;

E. The softswitch sends an initial address message to the circuit switching network through the called SS7 gateway, and the circuit switching network sends back the full address message, and the called party rings;

F. The softswitch sends a Modify command to the calling trunk media gateway, notifying to send a ringback tone;

G. The softswitch sends the full address message to the calling SS7 gateway.

If the called party picks up the phone after ringing, the call establishment method is as follows:

H. The called party picks up the phone, and the called SS7 gateway sends a response message to the softswitch;

1, the softswitch sends a Modify command to the calling trunk media gateway to cut off the ringback tone;

J. The softswitch sends a response message to the calling SS7 gateway.

The beneficial effects of the present invention are: the present invention improves the defect of the call flow suggested by the standard according to the experience in the actual implementation process, and before the softswitch sends the IAM sent by the calling SS7 signaling gateway to the called signaling gateway, The calling trunk gateway has been controlled to obtain the IP address and port number of the called RTP endpoint through the Modify request, so the trunk gateway has been controlled to complete the establishment of the media stream before the softswitch sends the IAM. Therefore, even after the called party rings Immediate off-hook will not cause the media stream not to be established after off-hook, and the present invention provides a more complete method for establishing call flow.

Description of drawings

FIG. 1 is a schematic diagram of an existing call setup process initiated by a trunk media gateway;

Fig. 2 is a schematic diagram of the call establishment process initiated by the relay media gateway in the present invention.

Detailed ways

The present invention will be described in further detail below according to accompanying drawing and embodiment:

As shown in Figure 2, to solve the above problems need to control the timing of softswitch sending IAM, this call setup process of the present invention is as follows,

(1) After the user dials, the IAM is sent to the softswitch through the calling SS7 gateway (SG1).

(2) Create a new association in the calling trunk media gateway (TMG1), and add a semi-permanent termination point (TDM) and a temporary termination point (RTP) in the association.

(3) Create a new association in the called trunk media gateway (TMG2), and add a semi-permanent termination point (TDM) and a temporary termination point (RTP) in the association.

(4) The soft switch sends a Modify command to TMG1 to inform the remote RTP port number and IP address.

(5) The soft switch sends the IAM to the circuit switching network through the called SS7 gateway (SG2), and the circuit switching network sends back the ACM, and the called party rings.

(6) The softswitch sends a Modify command to TMG1, notifying to send a ringback tone.

(7) The soft switch sends the ACM to SG1.

(8) After the called party picks up the hook, SG2 sends ANM to the softswitch.

(9) The softswitch sends a Modify command to TMG1 to cut off the ringback tone.

(10) The softswitch sends ANM to SG1.

After this modification, even if the called party goes off-hook immediately after ringing, the softswitch has already controlled the trunk gateway to complete the establishment of the media stream before sending the IAM, so the situation that the media stream has not been established after off-hook will not occur.

Claims (2)

1. the method for building up of a call flow may further comprise the steps:

After A, the subscriber dialing, send initial address message to soft switch by caller Signaling System Number 7 gateway;

B, new association of establishment in the caller Trunk Media Gateway, and in association, add semipermanent destination node and provisional destination node;

C, new association of establishment in called Trunk Media Gateway, and in association, add semipermanent destination node and provisional destination node;

D, soft switch send the Modify order to the caller Trunk Media Gateway, inform provisional destination node port numbers of far-end and IP address;

E, soft switch send initial address message by called Signaling System Number 7 gateway to Circuit Switching Network, the full message of Circuit Switching Network's loopback address, called terminal ringing;

F, soft switch send the Modify order to the caller Trunk Media Gateway, and notice sends ring-back tone;

G, soft switch send Address Complete Message to caller Signaling System Number 7 gateway.

2. according to the method for building up of the call flow shown in the claim 1, it is characterized in that: if off-hook behind the called terminal ringing, call-establishing method is as follows:

Behind H, the called off-hook, called Signaling System Number 7 gateway sends response message to soft switch;

I, soft switch send the Modify order to the caller Trunk Media Gateway, cut off ring-back tone;

J, soft switch send response message to caller Signaling System Number 7 gateway.

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