________________________________________
From: [email protected] 
[[email protected]] On Behalf Of Iñaki Baz 
Castillo [[email protected]]

Hi, is it valid the following (fragment of an) SDP?:

  m=audio 5970 RTP/AVP 18 0 4 8 96
  a=rtpmap:18 G729/8000
  a=rtpmap:0 PCMU/8000
  a=rtpmap:4 G723/8000
  a=rtpmap:8 PCMA/8000
  a=rtpmap:96 telephone-event/8000

I know that RFC 2833 or 4733/4734 do not mandate a specific payload
value for DTMF, but AFAIK values below 100 are reserved, am I wrong?
This is, values below 100 are supposed to indicate standarized values
(as some codecs). Please correct me if I'm wrong.
_______________________________________________

It is valid to assign a codec to payload 96.  IIRC, it is *valid* but not 
recommended
to assign a codec to any payload number, including those that have static 
assignments.

But historically, some Cisco gear only used payload 101 for receiving 
telephone-event,
even if the SDP specified a different payload number.  So it has become 
conventional
to always use 101 for telephone-event.

Dale

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