S.3 Application usage of SIP

24.2293GPPIP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP)Release 18Stage 3TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

S.3.1 Procedures at the UE

S.3.1.0 Void

S.3.1.0a IMS_Registration_handling policy

Not applicable.

S.3.1.1 P-Access-Network-Info header field

The UE may, but need not, include the P-Access-Network-Info header field where indicated in subclause 5.1.

S.3.1.1A Cellular-Network-Info header field

Not applicable.

S.3.1.2 Availability for calls

Not applicable.

S.3.1.2A Availability for SMS

Void.

S.3.1.3 Authorization header field

Void

S.3.1.4 SIP handling at the terminating UE when precondition is not supported in the received INVITE request, the terminating UE does not have resources available and IP-CAN performs network-initiated resource reservation for the terminating UE

Not applicable.

S.3.1.5 3GPP PS data off

Not applicable.

S.3.1.6 Transport mechanisms

No additional requirements are defined.

S.3.1.7 RLOS

Not applicable.

S.3.2 Procedures at the P-CSCF

S.3.2.0 Registration and authentication

Void.

S.3.2.1 Determining network to which the originating user is attached

In order to determine from which network the request was originated the P-CSCF shall check if the location information received in the network provided and/or UE provided "dvb-rcs2-node-id" parameter in the P-Access-Network-Info header field(s) indicates that the UE is connected to the same network as the P-CSCF or not.

NOTE 1: If local policy does not require the insertion of P-Access-Network-Info header field in the P-CSCF even if it is missing in the received initial request, the P-CSCF can assume that the request is initiated by a UE in the same network as the P-CSCF.

NOTE 2: If the location information in the network provided and UE provided "dvb-rcs2-node-id" parameters (in a request that includes two P-Access-Network-Info header fields) is contradictory, or the two P-Access-Network-Info header fields indicate different access types the P-CSCF ignores either the network provided or the UE provided information according to operator policy.

S.3.2.2 Location information handling

Upon receipt of an initial request for a dialog or standalone transaction or an unknown method, the P-CSCF based on local policy may include a P-Access-Network-Info header field. The value of the "dvb-rcs2-node-id" parameter shall be provided by the IP-CAN.