back to TS 24.228
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IMS S5 signalling flow - Session Initiation: Mobile origination and termination in home network, but terminating UE roaming and busy - IMS S5-1c. SIP INVITE request (UE1 to UE2): from P-CSCF1 to S-CSCF1
  • Request-URI: In the case where the Request-URI of the incoming INVITE request to S-CSCF contains a TEL-URL, it has to be translated to a globally routable SIP-URL before applying it as Request-URI of the outgoing INVITE request. For this address translation the S-CSCF uses the services of an ENUM-DNS protocol according to RFC 2916, or any other suitable translation database.
  • P-Charging-Vector: The S-CSCF adds the identifier of its own network to the originating Inter Operator Identifier (IOI) parameter of this header.