CN1501650A - A method for establishing a call flow - 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 If it 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: Answer Message), etc.

The existing call flow is as follows:

(1) The user dials and sends (IAM) to the softswitch through the No. 7 signaling gateway.

(2) Create a new association 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 the IAM to the circuit switching network through the SS7 gateway, and the circuit switching network sends back the ACM, and the called party rings.

(5) The soft switch sends a Modify command to TMG1, notifies the remote RTP port number and IP address, and notifies sending 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 No. 7 signaling gateway sends the IAM sent by the softswitch to the circuit The switching network, the circuit switching network sends back the ACM, and the called party rings, but the softswitch receives the ACM sent back from the circuit switching network through the No. 7 signaling gateway, and then controls the calling trunk gateway to obtain the IP of the called RTP termination point through the Modify request address and port number, and then the relay gateway completes the establishment of the media stream with 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 (IAM) to the softswitch through the No. 7 signaling gateway;

B. Create a new association (Context) in the calling trunk media gateway, and

Add semi-permanent endpoints and temporary endpoints to ;

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

Persistent endpoints and temporary endpoints;

D. The softswitch sends a Modify command to the calling trunk media gateway to inform the remote end of the temporary

Endpoint port number and IP address;

E. The soft switch sends the initial address message to the circuit switched network through the No. 7 signaling gateway

(IAM), circuit switching network loopback address full message (ACM), 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 soft switch sends an Address Complete Message (ACM) to the calling signaling gateway.

  After the called party rings and picks up the phone, the call establishment method is as follows:

H, called off-hook, called signaling gateway sends answer message (ANM) to softswitch;

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

J. The soft switch sends an answer message (ANM) to the calling signaling gateway.

The beneficial effects of the present invention are: the present invention improves the defects of the call flow suggested by the specification according to the experience in the actual implementation process, and before the soft switch sends the IAM sent by the calling signaling gateway to the called signaling gateway, it has passed Modify requests to control the calling trunk gateway to obtain the IP address and port number of the called 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 call immediately after ringing The situation that the media flow has not been established after off-hook does not occur, and the invention provides a more complete method for establishing a 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) The user dials up and sends the IAM to the softswitch through the No. 7 signaling gateway.

(2) Create a new association 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 a Modify command to TMG1 to inform the remote RTP port number and IP address.

(5) The softswitch sends the IAM to the circuit switching network through the SS7 gateway, 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) The called party picks up the hook, and 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. A method for establishing a call flow, comprising the following steps: A. The user dials, and sends an initial address message (IAM) to the softswitch through the No. 7 signaling gateway; B. Create a new association (Context) in the calling trunk media gateway, and Add semi-permanent endpoints and temporary endpoints to ; C. Create a new association in the called trunk media gateway, and add semi-permanent to the association Persistent endpoints and temporary endpoints; D. The softswitch sends a Modify command to the calling trunk media gateway to inform the remote end of the temporary Endpoint port number and IP address; E. The soft switch sends the initial address message to the circuit switched network through the No. 7 signaling gateway (IAM), circuit switching network loopback address full message (ACM), 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 soft switch sends an Address Complete Message (ACM) to the calling signaling gateway. 2. according to the establishment method of the call flow shown in claim 1, it is characterized in that: if the called party goes off-hook after ringing, the call establishment method is as follows: H, called off-hook, called signaling gateway sends answer message (ANM) to softswitch; 1, the softswitch sends a Modify command to the calling trunk media gateway to cut off the ringback tone; J. The soft switch sends an answer message (ANM) to the calling signaling gateway.

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