SIP/2.0 200 OK
Via: SIP/2.0/UDP nm;branch=foo;rport=26810;received=224.217.173.226
From: <sip:nm@nm>;tag=root
To: <sip:nm2@nm2>;tag=159244889016297465762084799838
Call-ID: 50000
CSeq: 42 OPTIONS
Allow: INVITE, ACK, OPTIONS, BYE, CANCEL, UPDATE, INFO, SUBSCRIBER, NOTIFY, MESSAGE, PRACK, REFER
Accept: application/sdp
User-Agent: eXosip/3.6.0
Allow-Events: dialog, message-summary, refer, reg, ua-profile
Content-Length: 0