INVITE sip:123@y.y.y.y:5060;user=phone SIP/2.0
Via: SIP/2.0/UDP  x.x.x.x:5060
From: <sip:4957771723@x.x.x.x>;tag=36C9D770-13E9
To: <sip:123@y.y.y.y;user=phone>
Date: Tue, 25 Dec 2007 11:54:35 GMT
Call-ID: FEF1192C-B21611DC-A631B649-7450F503@x.x.x.x
Supported: 100rel
Cisco-Guid: 4277213484-2987790812-2788144713-1951462659
User-Agent: Cisco-SIPGateway/IOS-12.x
CSeq: 101 INVITE
Max-Forwards: 6
Timestamp: 1198583675
Contact: <sip:4957771723@x.x.x.x:5060;user=phone>
Expires: 180
Content-Type: application/sdp
Content-Length: 240

v=0
o=CiscoSystemsSIP-GW-UserAgent 7336 7296 IN IP4 x.x.x.x
s=SIP Call
c=IN IP4 x.x.x.x
t=0 0
m=audio 16924 RTP/AVP 8 0 101
a=rtpmap:8 PCMA/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15