Content for  TS 23.280  Word version:  19.3.1

This provides the capability for an MC service user to migrate to another MC system during an ongoing group communication and to continue the group communication in the other MC system.

The procedure is based on the following existing procedures:

• MC service group de-affiliation procedure as described in clause 10.8.4.2, or
• De-affiliation from MC service group(s) defined in partner MC service system as described in clause 10.8.4.3.
• MC service user receiving MC service from a partner MC system as described in clause 10.1.4.3.2.
• MC service group affiliation procedure as described in clause 10.8.3.1, or
• Affiliation to MC service group(s) defined in partner MC system as described in clause 10.8.3.2 or clause 10.8.3.2a.
• Late entry MCPTT group call as described in clause 10.6.2.3.1.1.4 of TS 23.379 (pre-arranged group call) and clause 10.6.2.3.1.2.5 of TS 23.379 (chat group call).
• Late entry MCVideo group call as described in clause 7.1.2.3.1.1.4 of TS 23.281 (pre-arranged) and clause 7.1.2.3.1.2.6 of TS 23.281 (chat group call).

Pre-conditions:

1. The MC service client is a receiving party in one or more ongoing group calls in the primary MC system.
2. The MC service UE detects the need to change the MC system.

The MC service client may indicate the successful migration of group communications to the MC service user.

This provides the possibility for an MC service user to initiate a private MC service call using a functional alias, defined in the partner MC system, as target address towards an MC service user in a partner MC system.

Figure 10.16.3.3-1 represents a generic MC service private call setup procedure to allow using the functional alias as called party address, i.e., the MC service ID address is resolved by the partner MC system through the primary MC service server and primary MC service functional alias controlling server. Additional new pre-condition:

1. A secured connection has been established between the MC service functional alias controlling servers in different MC systems.

This subclause provides a generic guidance on the behaviour an MC service client follows to perform migration during an ongoing private communication, e.g., MCPTT private call. Once the MC service client detects the need to migrate during an ongoing private communication, it may initiate preparations and UE configuration which facilitate migration as mentioned in clause 10.1.1.2. The described procedure is applicable to the scenarios whether an MC service client is migrating into its primary MC system or a partner MC system.

Figure 10.16.4.2-1 represents a generic procedure to be followed when migration is needed to be done during an ongoing private communication, such as MCPTT private call, or MCVideo private call.

This subclause describes a generic private communication procedure towards a migrated MC service user at a partner MC system. This generic private communication can be an MCPTT private call, an MCVideo private call, or a one-to-one MCData communication. For the generic private call, this procedure is used in conjunction with the corresponding MCPTT, MCVideo and MCData procedures described in TS 23.379, TS 23.281, or TS 23.282, respectively. Once an MC service user is migrated, he or she will be assigned a new MC service ID by the migrated MC system and this MC service ID will be used for all his/her communications. When another MC service user communicates with the migrated MC service user using the newly assigned MC service ID, the private call request described in clause 10.7.2.1.1 of TS 23.379, in clause 7.2.2.2.1 of TS 23.281, or the corresponding procedures in TS 23.282 applies. For callers that are not aware of the migrated MC service user`s new MC service ID, the migrated MC service user is also reachable by his/her MC service ID assigned by the primary MC system via redirection done by the primary MC system`s MC service server described in this procedure.

Table 10.16.5.2-1 describes the information flow of a private call redirection, which is sent from the MC service server to an MC service client initiating a private call towards a migrated MC service user.

Figure 10.16.5.3-1 presents a generic private communication procedure from MC service user 1 towards a migrated MC service user 2 where the MC system A is the primary MC system of MC service user 2 before migration, and the MC system B is the MC system that the MC service user 2 has migrated Pre-conditions:

• MC system A and MC system B are interconnected.
• MC system A is the primary MC system of MC service user 2 before migration. MC system B is the MC system that MC service user 2 has migrated.
• The MC service server A is aware that MC service user 2 has migrated and is informed of its MC service ID provided by MC system B, as described in clause 10.6.3.3.