INVITE sip:UserB@example.com SIP/2.0
Via: SIP/2.0/UDP iftgw.example.com
From: <sip:+13035551111@ift.client.example.net;user=phone>
Record-Route: <sip:UserB@example.com;maddr=ss1.example.com>
To: sip:+16505552222@ss1.example.net;user=phone
Call-ID: inv2543.1717@ift.client.example.com
CSeq: 56 INVITE
Content-Type: application/sdp

v=0
o=mhandley 29739 7272939 IN IP4 192.0.2.5
s=-
c=IN IP4 192.0.2.5
t=0 0
m=audio 49217 RTP/AVP 0
