5.1.3 SDP handling

32.2603GPPCharging managementIP Multimedia Subsystem (IMS) chargingRelease 17Telecommunication managementTS

SDP information on SIP can have two different meanings; SDP offer or SDP answer. This is captured in the charging information by a SDP-type parameter that indicates if the SDP Media Component is an SDP offer or SDP answer. SDP offers can be sent by either the calling or called party and the Media Initiator Flag identifies who sent the first SDP offer in a SDP negotiation. SDP can be negotiated more than once in an SIP INVITE or SIP RE-INVITE dialog.

Each occurrence of the List of SDP Media Components in the corresponding CDRs may include either SDP offer or SDP answer. For the first negotiation, the SDP answer defines which media are used in the session, therefore it shall be recorded in case of successful session setup. Additionally the corresponding SDP offer may be recorded. In case of unsuccessful session setup the SDP offer may be recorded, if available.

When session re-negotiations occur, multiple occurrences of List of SDP Media Components may be used to include a series of SDP negotiations in which each occurrence holds an SDP offer or SDP answer as for the first SDP negotiation.