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TS 24.228 – §7.2.2 – §7.3.2 – §7.4.2   List   Prev   Next
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IMS S1 signalling flow - Session Initiation: Mobile origination and termination roaming, with different network operators - IMS S1-2a. SIP 183 Session Progress response: from UE2 to P-CSCF2
  • P-Access-Network-Info: UE2 provides the access-type and access-info, related to the serving access network.
  • To: A tag is added to the To header.
  • Contact: Contains a SIP URI with the IP address or FQDN of UE2. It includes the comp=sigcomp parameter.
  • SDP: The SDP contains the set of codecs supported UE2. It requests a confirmation of the QoS preconditions for establishing the session.
  • P-CSCF2 authorizes the resources necessary for this session. The approval of QoS commitment either happens at this stage or after 200 OK of INVITE based on operator local policy.