SIP/2.0 200 OK
Via: SIP/2.0/UDP nm;branch=foo;rport=26810;received=224.108.81.50
From: <sip:nm@nm>;tag=root
To: <sip:nm2@nm2>;tag=1938323633
Call-ID: 50000
CSeq: 42 OPTIONS
Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, SUBSCRIBE, NOTIFY, INFO, UPDATE, PRACK
Accept: application/sdp
User-Agent: eXosip/3.6.0
Content-Length: 0