IMS S1-8b. SIP PRACK request (UE1 to UE2): from P-CSCF1 to S-CSCF1

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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 S1-8b. SIP PRACK request (UE1 to UE2): from P-CSCF1 to S-CSCF1

P-CSCF1 removes the Security-Verify header and associated "sec-agree" option-tags prior to forwarding the request. As the Require and Proxy-Require headers are empty, it removes these headers completely.