7.2.5 Call clearing received from MGW

23.2313GPPRelease 17SIP-I based circuit-switched core networkStage 2TS

7.2.5.1 Bearer released on the access side

After the MSC server has received the Bearer Released procedure from the MGW on the access side, the MSC server shall release the access resources as described in clause 7.2.2.1. If the call is already established towards the network side, call clearing to the network side is performed as described in clause 7.2.3.2.

7.2.5.2 Bearer released on the network side

After the MSC server has received the Bearer Released procedure from the MGW on the network side, the MSC server shall clear the call to the network side as described in clause 7.2.3.2, and clear the call to the UE as described in clause 7.2.2.1.

7.2.5.3 Example Call Flow

Figure 7.2.5.3.1 shows the network model for an MGW initiated clearing of an established mobile call. The "squared" line represents the call control signalling. The "dotted" line represents the bearer control signalling (not applicable in A/Gb mode for the A-interface) and the bearer. The MSC server seizes one context with two bearer terminations in the MGW. Bearer termination T1 is used for the bearer towards RNC/BSC and bearer termination T2 is used for the bearer towards succeeding MGW.

Figure 7.2.5.3.1: MGW Initiated Call Clearing (Network model)

Figure 7.2.5.3.2 shows the message sequence example for the MGW initiated clearing of an established mobile call. After the MSC server is notified that the MGW has released the network side bearer, the MSC server initiates call clearing of the network side and the access side. After the call clearing towards the UE and the radio resource release have been completed the MSC server requests release of the access side bearer termination. Once the preceding/succeeding node has indicated that call clearing has been completed, the MSC server requests the release of the network side bearer termination.

Figure 7.2.5.3.2: MGW Initiated Call Clearing (message sequence chart)