Content for TS 23.231 Word version: 18.0.0
7.2.3 Call Clearing received from UE p. 36
7.2.3.1 Procedures towards access side p. 36
Call clearing from the UE shall be performed in accordance with clause 7.2.2.1 in TS 23.205.
7.2.3.2 Procedures towards network side p. 37
7.2.3.2.1 Call Clearing during call establishment p. 37
7.2.3.2.1.1 Originating MSC-S p. 37
If the MSC server has sent an initial INVITE request to the succeeding node, the MSC server shall apply SIP procedures detailed in RFC 3261 to terminate the corresponding SIP dialogue(s) and session(s), making use of CANCEL and/or BYE request(s).
The MSC server shall then perform the normal bearer release according to clause 7.2.6.
7.2.3.2.1.2 Terminating MSC-S p. 37
If the MSC server received an initial INVITE request from the preceding node and has not yet sent out a final response for the initial INVITE request, the MSC server shall send an appropriate failure response for the initial INVITE request to the preceding node.
The MSC server shall then perform the normal bearer release according to clause 7.2.6.
7.2.3.2.2 Call Clearing after call established p. 37
7.2.3.2.2.1 Originating MSC-S p. 37
If the MSC server has sent an initial INVITE request to the succeeding node and has received a final 200 OK (INVITE) response for the initial INVITE request, the MSC server shall send a BYE request to the succeeding node to release the call.
The MSC server shall then perform the normal bearer release according to clause 7.2.6.
If the call set-up fails and the MSC server plays an in-band tone or announcement to signal to the calling user the reason of the call failure, the MSC server shall initiate the call clearing with the SIP response code mapped from the ISUP cause No. 31 as specified in Table 9 of TS 29.163, and with encapsulated REL message with cause No. 31 "Normal, unspecified".
7.2.3.2.2.2 Terminating MSC-S p. 37
If the MSC server received an initial INVITE request from the preceding node and a successful final response for the initial INVITE request has been sent out, the MSC server shall send a BYE request to release the call.
The MSC server shall then perform the normal bearer release according to clause 7.2.6.
7.2.3.3 Example Call Flow p. 37
Figure 7.2.3.3.1 shows the network model for a user 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 7.2.3.3.2 shows the message sequence example for the user initiated clearing of an established mobile call. In the example the UE initiates call clearing towards the MSC server and the MSC server requests release of the radio resource. After the response of the radio resource release is received the MSC server requests the release of the access side bearer termination. The MSC server initiates call clearing towards the preceding/succeeding node. Once the preceding/succeeding node has indicated that call clearing has been completed, the MSC server releases the network side bearer termination.
Figure 7.2.3.3.2: User Initiated Call Clearing (message sequence chart)
(⇒ copy of original 3GPP image)
(⇒ copy of original 3GPP image)
