You cannot control the following SIP headers using relay or transparency flags in relay scenarios:
Accept-Language | Alert-Info | Also |
Anonymity | Authorization | Contact |
Content-Length | Diversion | Error-Info |
Event | Expires | From |
Max-Forwards | Min-Expires | Min-SE |
Path | P-Charge-Info | P-DCS-Billing-Info |
P-K-Cfl | P-K-Cfo | P-Preferred-Identity |
Proxy-Authenticate | Proxy-Authorization | Proxy-Require |
P-Sig-Info | RAck | Reason |
Record-Route | Remote-Party-ID | Reply-To |
Requested-By | Require | Resource-Priority |
Retry-After | RSeq | Service-Route |
Session-Expires | Subscription-State | To |
Via | Warning | WWW-Authenticate |