SIP/2.0 404 Not Found
Via: SIP/2.0/UDP nm;branch=foo;rport=26810;received=224.45.39.191
From: <sip:nm@nm>;tag=root
To: <sip:nm2@nm2>;tag=B396F5F2D1B0A899
Call-ID: 50000
CSeq: 42 OPTIONS
User-Agent: FRITZ!OS
Content-Length: 0