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SIP ↠  ExamplesGrammarsPresence ⇾  MainServicesTransactionDialogIMS
TS 24.228§7.2.3§7.3.5§7.4.5   List   Prev   None
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IMS S5 signalling flow - Session Initiation: Mobile origination and termination in home network, but terminating UE roaming and busy - sequence chart for IMS S5-1. SIP INVITE request (UE1 to UE2)
  • The UE is located in the home network, and determines the P-CSCF via the CSCF discovery procedure.
  • The P-CSCF knows the name/address of the S-CSCF from a prior Registration performed by the UE.