SIP/2.0 200 OK
Via: SIP/2.0/UDP nm;rport=26810;received=224.208.157.5;branch=foo
Call-ID: 50000
From: <sip:nm@nm>;tag=root
To: <sip:nm2@nm2>;tag=foo
CSeq: 42 OPTIONS
Allow: PRACK, INVITE, ACK, BYE, CANCEL, UPDATE, SUBSCRIBE, NOTIFY, REFER, OPTIONS
Accept: application/sdp, application/simple-message-summary, message/sipfrag;version=2.0
Supported: replaces, 100rel, timer, norefersub
Allow-Events: message-summary, refer
User-Agent: TP-Link SIP Stack V1.0.0
Content-Type: application/sdp
Content-Length:   300

v=0
o=- 3946757798 3946757798 IN IP4 151.81.53.11
s=pjmedia
c=IN IP4 151.81.53.11
t=0 0
m=audio 60000 RTP/AVP 18 8 0 96
a=rtcp:60001 IN IP4 151.81.53.11
a=rtpmap:18 G729/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:0 PCMU/8000
a=sendrecv
a=ptime:0
a=rtpmap:96 telephone-event/8000
a=fmtp:96 0-15