[Freeswitch-dev] DTMF dropped due to remote party re-starting packet numbers from 0 for each digit

[Andy Newlands]

Hi,

A 3rd-party is sending each RFC2833  DTMF digit with a new SSRC and starts
the packet sequence numbering at ZERO for each new digit.

I can see, in switch_rtp.c: handle_rfc2833(), that FS makes a note (in the
session) of the last DTMF packet it processed, then drops any subsequent
packets with a sequence number less than that.

My questions are:

1. Is the remote-party compliant with relevant RFCs when they set a new
SSRC for each DTMF digit?
2. Is the remote party compliant with relevant RFCs when they re-start
packet sequence numbers from 0 for each DTMF digit?
3. Looking at the source for handle_rfc2833(), I can't see any setting
which could be used to force FS to 'tolerate' the above behaviour
4. If I alter handle_rfc2833(), to cope with that behaviour, am I likely to
run into problems with other remote systems (E.G. possibly ending up with
duplicate digits)

Thanks,

Andy
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