add fmtp along with rtpmap on the SDP

Hi guys 

 

I have noticed we get "488 unable to parse SDP" reply from Lync Mediation server when i send an INVITE without ftmp header for 101 telephone-event. I have "a=rtpmap:101 telephone-event/8000" just in the SDP on the INVITE and apparently lync expects "a=fmtp:101 0-15" as well along with the rtpmap header. 

 

Working SDP on the INVITE:

 

v=0
o=BroadWorks 132656896 1 IN IP4 93.187.224.124
s=-
t=0 0
m=audio 21426 RTP/AVP 8 101
c=IN IP4 93.187.224.124
a=rtpmap:8 PCMA/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
a=sqn:0
a=cdsc:1 image udptl t38
a=sendrecv

 

 

Rejected SDP on INVITE with missing ftpmap: 

 

v=0
o=BroadWorks 131037336 1 IN IP4 212.98.65.50