SIP Contact

INVITE sip:bob@biloxi.com SIP/2.0
Via: SIP/2.0/UDP pc33.atlanta.com:5060;branch=z9hG4bK776asdhds
To: Bob <sip:bob@biloxi.com>
From: Alice <sip:alice@atlanta.com>;tag=1928301774
Call-ID: a84b4c76e66710
CSeq: 314159 INVITE
Contact: <sip:alice@pc33.atlanta.com>
Content-Type: application/sdp
Content-Length: 142
(Alice’s SDP not shown)

Contact header contains a SIP URL for direct communication between User Agents

If Proxies do not Record-Route†, they can be bypassed

Contact header is also present in the 200 OK response

^† Note that the Record-Route and Route headers approach of RFC 2543 was found not to work.

Transcript

[slide134] The contact information, which might be another way of contacting, in this case, Alice,