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SIP ↠  ExamplesGrammarsPresence ⇾  MainServicesTransactionDialogIMS
TS 24.228§7.2.3§7.3.5§7.4.3   List   Prev   Next
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IMS S2 signalling flow - Session Initiation: mobile origination and termination in home network - IMS S2-2a. 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 the UE; it includes the comp=sigcomp parameter.
  • SDP: Contains the set of codecs supported by 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.