Does the SIP un-register tag value (in the From: field) should match the register tag value? i.e. if:
REGISTER sip:registrar.biloxi.com SIP/2.0 Via: SIP/2.0/UDP bobspc.biloxi.com:5060;branch=z9hG4bKnashds7 Max-Forwards: 70 To: Bob <sip:[email protected]> From: Bob <sip:[email protected]>;tag=456248
Does the un-register MUST use the same tag=456248?