Content for &nbsp; TS 23.379 &nbsp; Word version:&nbsp; 19.1.0

The affiliated MCPTT user via MCPTT client initiates a group call with an MCPTT group ID. A group call request message with the MCPTT group ID is routed to the MCPTT server of the primary MCPTT system, which owns the group and is where the authorized MCPTT user/dispatcher created the temporary group. If the group call is for a temporary group formed by the group regroup procedure, the MCPTT group ID will be a temporary MCPTT group ID.

The MCPTT server of the primary MCPTT system gets the group information (either from group management server or itself) including the constituent MCPTT groups' identities, accessible group members list of the constituent groups, and other related data.

The MCPTT server of the primary MCPTT system initiates directly a call request to the accessible group members using the detailed user information and/or location information. The group members upon receipt of the call request may accept or reject the call.

The MCPTT server of the primary MCPTT system may not have access to group members' information of the constituent group belonging to the partner MCPTT system. For such group members, the MCPTT server of the primary MCPTT system initiates a group call request message to the MCPTT server of the partner MCPTT system with the target group's MCPTT group ID information.

The MCPTT server of the partner MCPTT system further initiates a call request to the constituent group's members as described in step 3.

Figure 10.6.2.4.1.1.2-1: Non-broadcast group call involving groups from multiple MCPTT systems (terminating)

The MCPTT server of the partner MCPTT system provides a group call response to the MCPTT server of the primary MCPTT system with success or failure result and/or detailed reason information if there is a failure.

Step 7.

The MCPTT server of the primary MCPTT system provides a group call response message to the MCPTT client of the affiliated MCPTT user upon receiving responses to the call requests sent to members of primary and partner MCPTT systems. The group call response message will consist of the success or failure result and/or detailed reason information if there is a failure.

Step 8.

Upon successful call setup completion a group call is established for the group members from constituent groups of multiple MCPTT servers.

10.6.2.4.1.1.2 Group call setup procedure - terminating side p. 66

The procedure in Figure 10.6.2.4.1.1.2-1 illustrates the terminating side group call involving groups from multiple MCPTT systems. It considers the scenario for group hierarchies and non-broadcast temporary groups formed by group regroup. The protocol followed may be SIP.

Reproduction of 3GPP TS 23.379, Fig. 10.6.2.4.1.1.2-1: Non-broadcast group call involving groups from multiple MCPTT systems (terminating)

The MCPTT server of the primary MCPTT system sends the group call request message to the MCPTT server(s) of the partner MCPTT system.

The MCPTT server of the partner MCPTT system determines whether to forward the group call request message to the MCPTT client(s) based on the user affiliation.

The MCPTT server of the partner MCPTT system forwards the group call request message to MCPTT client(s). The MCPTT server indicates whether acknowledgement is required for the call.

The MCPTT user is notified about the incoming MCPTT group call.

The receiving MCPTT client(s) accept the group call request and a group call response message is sent to the MCPTT server of the partner MCPTT system. This response may contain an acknowledgement. The conditions for sending acknowledgement may be based on configuration.

Figure 10.6.2.4.1.2-1: Group call release involving groups from multiple MCPTT systems

The MCPTT server of the partner MCPTT system forwards the group call response message to the MCPTT server of the primary MCPTT system (i.e. group hosting MCPTT server for the group call involving groups from multiple MCPTT systems).

10.6.2.4.1.2 Group call release p. 66

The procedure focuses on the case where the group host MCPTT server releases an ongoing MCPTT group call for all the participants of that group call involving groups from multiple MCPTT systems, since at least one of the release conditions are met e.g., due to hang time expiry, last participant leaving, second last participant leaving, initiator leaving, or minimum number of affiliated MCPTT group members are not present.

Figure 10.6.2.4.1.2-1 illustrates the procedure for the MCPTT server releasing an ongoing MCPTT group call involving groups from multiple MCPTT systems.

Pre-conditions:

The MCPTT server of the primary MCPTT system is controlling the group call involving groups from multiple MCPTT systems.
The MCPTT client 1 belongs to group of the MCPTT server of the primary MCPTT system and the MCPTT client 2 and client 3 belong to the groups of the MCPTT server of the partner MCPTT system.
The MCPTT users on MCPTT client 1, client 2 and client 3 are already part of the ongoing group call (e.g., as a result of group call setup involving groups from multiple MCPTT systems).

Reproduction of 3GPP TS 23.379, Fig. 10.6.2.4.1.2-1: Group call release involving groups from multiple MCPTT systems

The MCPTT server of primary MCPTT system would like to release the MCPTT group call which is ongoing e.g., due to hang timer expiry, last participant leaving, second last participant leaving, initiator leaving, or minimum number of affiliated MCPTT group members are not present.

The MCPTT server of the primary MCPTT system identifies the participants of the ongoing group call and generates group call release message to release ongoing session.

The MCPTT server of the primary MCPTT system initiates a group call release request message via SIP core towards each accessible participant of the ongoing group call (3a). The MCPTT server of the primary MCPTT system may not have access to group members' information of the constituent group belonging to a partner MCPTT system. For such group members, the MCPTT server of the primary MCPTT system initiates a group call release request message (3b) to the MCPTT server(s) of the partner MCPTT system(s) with the target group's MCPTT group ID information. The MCPTT server(s) of the partner MCPTT system(s) further initiate group call release request messages (3c-1, 3c-2) to its group's users.

The MCPTT users are notified about the release of the group call.

The MCPTT client(s) receiving the group call release request messages provide group call release response to the MCPTT server of the primary MCPTT system. The MCPTT client(s) of the MCPTT users belonging to partner MCPTT system(s) route their responses via the MCPTT server(s) of the partner MCPTT system(s).

Figure 10.6.2.4.2-1: Group call involving non-broadcast temporary group formed by group regroup from multiple MCPTT systems

The MCPTT client 1, client 2 and client 3 have successfully released the floor control and media plane resources associated with the group call that is released.

10.6.2.4.2 Group call for non-broadcast temporary group formed by group regroup procedure involving multiple MCPTT systems via trusted mode p. 68

Figure 10.6.2.4.2-1 illustrates a group call involving a non-broadcast temporary group formed by group regroup from multiple MCPTT systems. The protocol followed may be SIP.

Pre-conditions:

The security aspects of sharing the user information between primary and partner MCPTT systems shall be governed as per the service provider agreement between them. In this case, we consider the partner MCPTT system shares their users' information to the primary MCPTT system.
The MCPTT user belongs to an MCPTT group hosted by the primary MCPTT system.
A non-broadcast temporary group is formed by authorized MCPTT user/dispatcher by the group regroup procedure (subclause 10.2.4.2 in TS 23.280) and identified via a temporary MCPTT group ID.
The MCPTT group members of the constituent MCPTT groups belonging to the temporary group are affiliated to participate in a group call for the temporary group.
The authorized MCPTT user/dispatcher created the temporary group on the MCPTT server of the primary MCPTT system.
The constituent groups of the temporary group may belong to MCPTT servers of the partner MCPTT systems.

Reproduction of 3GPP TS 23.379, Fig. 10.6.2.4.2-1: Group call involving non-broadcast temporary group formed by group regroup from multiple MCPTT systems

The affiliated MCPTT user via MCPTT client initiates a group call with an MCPTT group ID. A group call request message with the MCPTT group ID is routed to the MCPTT server of the primary MCPTT system, which owns the temporary group formed by group regroup procedure, and is also where the authorized MCPTT user/dispatcher has created the temporary group. The MCPTT group ID will be a temporary MCPTT group ID.

The MCPTT server of the primary MCPTT system gets the group information (either from group management server or itself) including the constituent MCPTT groups' identities, and other related data.

The MCPTT server of the primary MCPTT system may interrogate the MCPTT server of the partner MCPTT system for the affiliated group 2 members.

The MCPTT server of the partner MCPTT system responds with a list of the affiliated group members of group 2.

The MCPTT server of the primary MCPTT system verifies the commencement policies of the temporary group, and initiates a call invitation or call notification to the affiliated members of groups 1 and 2.