v=0
o=root 20108 20108 IN IP4 202.6.138.139
s=session
c=IN IP4 202.6.138.139
t=0 0
m=audio 11062 RTP/AVP 18 101
a=rtpmap:18 G729/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=silenceSupp:off - - - -