This procedure enables originating and terminating UE to establish application data channels for the same application to communicate with the same Data Channel Application Server.
The P2A2P procedure requires the establishment of application data channels from UE#1 to MF and from UE#2 to MF. The two application data channels are associated with the same application. This enables UE#1 and UE#2 to interact with the same DC Application Server simultaneously and the DC Application Server to correlate the data exchanged with both UEs. The P2A procedures as described in clause AC.7.2 are used to establish one application data channel between UE#1 and MF and, for A2P scenario, one application data channel between UE#2 and MF. In case of two involved UEs, this enables independent communication between UE#1 and UE#2 with the DC Application Server.
UE#1 sends SIP re-INVITE request with an updated SDP to IMS AS. The updated SDP contains the bootstrap data channel, the application data channel information and associated DC application binding information.
The DCSF determines how to process the application data channel establishment request based on the parameters (i.e. associated DC application binding information) in the notification from IMS AS and/or DCSF service specific policy.
DCSF determines that the added application data channel media in the SDP offer requires the DC Application Server is the endpoint for both originating and terminating UE and that the application DC must be anchored at the MF or MRF. DCSF communicates with the DC Application Server for DC resource control. Once the application data channel is established, the DC Application Server will send/receive traffic to/from UE#1 through the MDC2 interface.
UE#2 and terminating network return 200 OK with SDP answer for audio/video and for the application data channel. The terminating network P-CSCF executes QoS procedure for application data channel media based on the SDP in the 200 OK. Based on the received DC Application binding information in the re-INVITE, UE#2 may need to download the corresponding DC Application signalled in the SDP offer, if not done already and associate it with the requested application DC.