Content for  TS 23.379  Word version:  19.4.0

Table 10.7.5.1.2-1 describes the information flow of the MCPTT private call forwarding request from the MCPTT client to the MCPTT server and MCPTT server to MCPTT server.

Table 10.7.5.1.3-1 describes the information flow of the MCPTT private call forwarding response from the MCPTT server to the MCPTT client.

Table 10.7.5.1.4-1 describes the information flow of the MCPTT private call forwarding request from the MCPTT server to the MCPTT client.

Table 10.7.5.1.5-1 describes the information flow of the MCPTT private call forwarding response from the MCPTT client to the MCPTT server and MCPTT server to MCPTT server.

An authorized user can update the call forwarding related parameters stored in the user profile using the procedures as defined in subclause 10.1.4.5 of TS 23.280.

Figure 10.7.5.2.2-1 below illustrates the procedure of immediate call forwarding of MCPTT private calls. Pre-conditions:

1. MCPTT client 2 is authorized to use call forwarding and has immediate call forwarding enabled with the destination MCPTT client 3.
2. MCPTT client 1 is authorized to make private calls to client 2.
3. The redirection counter is below the limit.
4. MCPTT client 1 has the necessary security information to initiate a private call with MCPTT client 2 and MCPTT client 3 if end2end encryption is required for the private call.

Figure 10.7.5.2.3-1 below illustrates the procedure of call forwarding no answer of MCPTT private calls. Pre-conditions:

1. MCPTT client 2 is authorized to use call forwarding and has call forwarding no answer enabled with the destination MCPTT client 3.
2. MCPTT client 1 is authorized to make private calls to MCPTT client 2.
3. No forwarding with no answer or based on manual user input has so far occurred in this call.
4. MCPTT client 1 has the necessary security information to initiate a private call with MCPTT client 2 and MCPTT client 3 if end2end encryption is required for the private call.

Figure 10.7.5.2.3a-1 below illustrates the procedure of call forwarding based on manual user input of MCPTT private calls. Pre-conditions:

1. MCPTT client 2 is authorized to perform call forwarding based on manual input.
2. MCPTT client 1 is authorized to make private calls to MCPTT client 2.
3. No forwarding with no answer or based on manual user input has so far occurred in this call.
4. MCPTT client 1 has the necessary security information to initiate a private call with MCPTT client 2 and MCPTT client 3 if end2end encryption is required for the private call.

If the target of the MCPTT private call forwarding has also any kind of MCPTT call forwarding activated generally the additional forwardings are performed sequentially. However, to avoid excessive numbers of forwardings and in particular to avoid indefinite loops in the forwarding a limit for immediate forwardings is defined in the service configuration. The MCPTT server keeps track of the number of forwardings, if the limit is exceeded, the call will be released. For forwarding no answer or for forwarding based on manual user input, only one forwarding is allowed, and in case of no answer on the first forwarding the MCPTT server will release the call.

The procedure describes the case for MCPTT for private call forwarding that an MCPTT user in a partner MCPTT system is the target of the MCPTT private call forwarding. Pre-conditions:

1. MCPTT client 2 is authorized to use call forwarding and has immediate call forwarding enabled with the destination MCPTT client 3.
2. MCPTT client 1 is authorized to make private calls to MCPTT client 2.
3. The redirection counter is below the limit.
4. MCPTT client 1 has the necessary security information to initiate a private call with MCPTT client 2 and MCPTT client 3 if end-to-end encryption is required for the private call.

The procedure for MCPTT private call forwarding describes the case of an MCPTT private call forwarding occurring in the partner MCPTT system. Pre-conditions:

1. MCPTT client 3 is authorized to use call forwarding and has immediate call forwarding enabled with the destination MCPTT client 2.
2. MCPTT client 1 is authorized to make private calls to MCPTT client 3.
3. The redirection counter is below the limit.
4. MCPTT client 1 has the necessary security information to initiate a private call with MCPTT client 2 and MCPTT client 3 if end-to-end encryption is required for the private call.