[asterisk-users] DTMF fun

[Tom Browning]

I'm chasing down some DTMF interop issues would like to hopefully rule
out Asterisk in the following configuration:

RTP path is:
Linux/PC/Mac SIP clients -> [MediaProxy as needed] -> Asterisk 1.8.7
-> SIP termination provider(s)

DTMF is strictly RFC2833 with no in-band.

Asterisk stays in the media path for application reasons and is
"Locally bridging SIP/foo and SIP/bar"

Asterisk is NOT configured to act on any DTMF while bridging the call
(no options re: DTMF on Dial() and no features enabled AFAIK).
(In the future, I may have Asterisk act on '*' key, but not yet)

The problem I'm seeing appears to be SIP client dependent
(Linux/PC/Mac).  The issue manifests itself when the client calls an
IVR/conference app on the far end and needs to enter DTMF keys to
interact (no surprise here!).

Counterpath's X-Lite appears to work 100% of the time with no issues.
Blink appears to work 95% of the time
2 other clients may work only 60% of the time

Looking at the RTP streams, all these clients send RFC2833 with slight
variations on a theme.

My question is this:  Is Asterisk simply relaying the client's DTMF
signalling untouched or do I need to look at Asterisk more
closely and turn some knobs.  I'm guessing that Locally Bridging
(without acting on any key) means that Asterisk is doing the
simplest of all possible things and just relaying the RTP packets, and
I need to just continue focusing on SIP clients and their interop with
distant and diverse gateways.

[I've read the Asterisk tickets about interop vs. RFC compliance but
I'm hoping to rule that out here as Asterisk is not originating the
DTMF]

Thanks