Content for  TS 23.379  Word version:  19.4.0

When an MCPTT user using a ProSe-enabled UE wants to communicate with a specific MCPTT user using a ProSe-enabled UE by a ProSe mechanism, the MCPTT client enables the use of the ProSe layer procedures for public safety, as specified in TS 23.303. The MCPTT client obtains configuration data such as the ProSe discovery group ID and user info ID of the target MCPTT user from the "List of user(s) who can be called in private call" in the MCPTT user profile and requests the IP address of the MCPTT UE associated with the target MCPTT user from the ProSe layer. The MCPTT client enables the ProSe layer to determine the IP address for the communication with the target MCPTT UE by providing the ProSe discovery group ID and user info ID (as defined in specification TS 23.303) of the target MCPTT user. This may trigger the ProSe direct discovery for public safety use procedure, described in TS 23.303, to identify whether the target MCPTT user is in the proximity of the calling MCPTT user. The user info ID of the target MCPTT user is used by the ProSe layer as the target info (as defined in specification TS 23.303). The ProSe layer can then provide the IP address related to the target MCPTT user's MCPTT ID to the MCPTT client. The establishment of the off-network private call using the ProSe capability is based on the one-to-one ProSe direct communication procedure described in TS 23.303.

The procedure focuses on the case where an MCPTT user is initiating an MCPTT private call for communicating with another MCPTT user when off-network using an automatic commencement mode. Procedures in Figure 10.7.3.3-1 are the basic signalling procedures for the MCPTT client initiating establishment of an off-network MCPTT private call with the chosen MCPTT user. Pre-conditions:

1. MCPTT user profile used for off-network operation mode is pre-provisioned in the MCPTT UEs.

The procedure focuses on the case where an MCPTT user is initiating an MCPTT private call for communicating with another MCPTT user when off-network using a manual commencement mode. Procedures in Figure 10.7.3.4-1 are the basic signalling procedures for the MCPTT client initiating establishment of an off-network MCPTT private call with the chosen MCPTT user. Pre-conditions:

1. MCPTT user profile used for off-network operation mode is pre-provisioned in the MCPTT UEs.

The procedure focuses on the case where an MCPTT client is requesting to release an ongoing MCPTT private call whether the call was established using either of the two commencement modes (manual or automatic), as described in subclause 10.7.3.3 and subclause 10.7.3.4. Either MCPTT client can initiate the call release procedure. Procedures in Figure 10.7.3.5-1 are the basic signalling control plane procedures for an MCPTT client initiating the release of an ongoing off-network MCPTT private call. Pre-conditions:

1. Two MCPTT users are currently engaged in an off-network MCPTT private call.

The off-network emergency private call is a special case of off-network private call as defined in subclause 10.7.3. The following are modifications to the aforementioned subclause to support MCPTT private calls:

• The call setup contains an indication that the MCPTT private call is to be an MCPTT emergency private call,
• the bearers of both MCPTT private call participants are given MCPTT emergency priority prior to media transfer,
• either participant in an MCPTT private call may upgrade the call to the MCPTT emergency state during the call by sending an MCPTT upgrade private emergency request,
• placing an MCPTT emergency private call places the MCPTT client in the MCPTT emergency state,
• the bearer priority of each participant is restored to the priority as it was prior to the MCPTT emergency private call initiation, when the call ends or when the MCPTT emergency priority is cancelled
• an authorized user or the originator of the call may cancel the MCPTT emergency priority of the call by sending an MCPTT cancel private emergency request and
• the MCPTT emergency priority of the MCPTT private call may be cancelled when criteria established by the MCPTT Administrator are met (e.g., timeout).

The MCPTT private call call-back request procedure includes the initial MCPTT private call call-back request from the MCPTT user and the indication to the receiving MCPTT user of the who called, the time when the call request was made, and the urgency indication. Procedures in Figure 10.7.4.2-1 show the signalling control plane procedures for the MCPTT client initiating an MCPTT private call call-back request with the chosen MCPTT user. Pre-conditions:

• MCPTT user 1 is the current user at MCPTT client 1 and MCPTT user 2 is the current user at MCPTT client 2;
• MCPTT client 1 and MCPTT client 2 are registered for MCPTT service.

Once an MCPTT private call call-back request has been successfully made and before the receiving MCPTT user has made an MCPTT private call to the calling MCPTT user, the calling MCPTT user may cancel the outstanding MCPTT private call request. Procedures in Figure 10.7.4.3-1 show the signalling control plane procedures for the MCPTT client initiating an MCPTT private call call-back cancel request with the chosen MCPTT user. Pre-conditions:

1. A previously successfully made MCPTT private call call-back request from MCPTT client 1 to MCPTT client 2.

Once an MCPTT private call call-back request has been successfully made, it is expected that the receiving MCPTT user will make an MCPTT private call to the MCPTT user who sent the MCPTT private call call-back request. The procedures for establishing the MCPTT private call between the two users is the same as an MCPTT private call (10.7.2.2.2). Procedures in Figure 10.7.4.4-1 show the signalling control plane procedures for the MCPTT client returning an MCPTT private call to the MCPTT user who initiated the MCPTT private call call-back request. Pre-conditions:

1. A previously successfully made MCPTT private call call-back request from MCPTT client 1 to MCPTT client 2.