[asterisk-users] RFC3389 message

[Kevin P. Fleming]

Tony Mountifield wrote:
> When making or receiving a SIP call via my service provider, I get the
> following message logged by Asterisk:
> 
> Dec 11 15:13:37 NOTICE[7392]: rtp.c:331 process_rfc3389: Comfort noise support incomplete in Asterisk (RFC 3389). Please turn off on client if possible. Client IP: xxx.xxx.xxx.xxx
> 
> Since the "client" is at my service provider (who uses CISCO kit, I believe),
> I don't have the ability to turn it off.

Well, this means that they are sending us RTP that we specifically
declined to accept (meaning we did not offer to support RFC3389 in our
SDP), which sucks because they are violating the protocol :-)

> My question is: what is the effect of leaving things as they are and just
> ignoring the message? What things might not behave properly?

It's bad because the timestamps of the audio will have gaps when
Asterisk drops the incoming CN packets. What effect this really has on
your system will depend on where you are sending that audio and what it
can do in terms of jitter buffering and other magic.

-- 
Kevin P. Fleming
Director of Software Technologies
Digium, Inc. - "The Genuine Asterisk Experience" (TM)