back to TS 24.228
- 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.
- P-Asserted-Identity: P-CSCF1 inserts the SIP URI in the P-Asserted-Identity header field and it also removes P-Preferred-Identity header field.
- P-Access-Network-Info: This header contains information from the UE.
- P-Charging-Vector: P-CSCF1 inserts this header and populates the icid parameters with a globally unique value.