INVITE sip:user@example.com SIP/2.0
Contact: <sip:caller@host5.example.net>
To: sip:j.user@example.com
From: sip:caller@example.net;tag=8392034
Max-Forwards: 70
Call-ID: invut.0ha0isndaksdjadsfij34n23d
CSeq: 235448 INVITE
Via: SIP/2.0/UDP somehost.example.com;branch=z9hG4bKkdjuw
Content-Type: application/unknownformat
Content-Length: 40

<audio>
 <pcmu port="443"/>
</audio>
