IMS S1-1d. SIP INVITE request (UE1 to UE2): from I-CSCF2 to S-CSCF2

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SIP ↠ Examples Grammars Presence ⇾ Main Services Transaction Dialog IMS

TS 24.228 – §7.2.2 – §7.3.2 – §7.4.2

IMS S1 signalling flow - Session Initiation: Mobile origination and termination roaming, with different network operators - IMS S1-1d. SIP INVITE request (UE1 to UE2): from I-CSCF2 to S-CSCF2

NOTE: I-CSCF2 does not add itself to the Record-Route header, as it has no need to remain in the signalling path once the session is established.
S-CSCF#2 validates the service profile of this subscriber and evaluates the initial filter criterias.