[Freeswitch-users] rtpmap question PCMU/PCMA

Mark Campbell-Smith mcampbellsmith at gmail.com
Mon May 31 07:12:48 PDT 2010

Hi All,

I'm sure I've discussed this before, but I searched through my gmail
and google and couldn't find the answer.

Below is the SDP parameters from my sip provider.  Is it mandatory to
always include the rtpmap details for PCMU/PCMA codes?  For example
something like 'a=rtpmap:8 PCMA/8000' and 'a=rtpmap:0 PCMU/8000'?

I'm using sipdroid on android and it rejects this with 'codec not supported'


o=Sippy 141730476 0 IN IP4 xxx.xxx.xxx.xxx
t=0 0
m=audio 47676 RTP/AVP 8 0 18 101
c=IN IP4 xxx.xxx.xxx.xxx
a=fmtp:18 annexb=yes
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
a=sqn: 0
a=cdsc: 1 audio RTP/AVP  8
a=cdsc: 2 image udptl t38
a=cpar: a=T38FaxUdpEC:t38UDPRedundancy
a=cpar: a=T38FaxVersion:0
a=cpar: a=T38MaxBitRate:14400

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