INVITE sip:bob@one.example.com SIP/2.0
Via: SIP/2.0/UDP sip.example.com;branch=7c337f30d7ce.1
  ;maddr=239.128.16.254;ttl=16
Via: SIP/2.0/UDP mouse.wonderland.com
From: Alice <sip:alice@wonderland.com>;tag=1
To: Bob <sip:bob@example.com>
Call-ID: 602214199@mouse.wonderland.com
CSeq: 1 INVITE
Contact: Alice <sip:alice@mouse.wonderland.com>
Subject: SIP will be discussed, too
Content-Type: application/sdp
Content-Length: 226

v=0
o=user1 53655765 2353687637 IN IP4 128.3.4.5
s=Mbone Audio
t=3149328700 0
i=Discussion of Mbone Engineering Issues
e=mbone@somewhere.com
c=IN IP4 224.2.0.1/127
t=0 0
m=audio 3456 RTP/AVP 0
a=rtpmap:0 PCMU/8000