[Asterisk-Dev] Sipura & RFC2833 - not sure if it's working

[Brent Goran]

I am using Asterisk out of CVS, and have a Sipura 1001. I've set
Asterisk's dtmfmode to RFC2833, and the Sipura set to use "AVT" for it's
DTMF transmit mode.

I can't seem to figure out whether or not RFC2833 is actually being
used, vs. inband. The reliability of my DTMF-based application is poor
(whereas it's perfect over IAX), which leads me to believe that RFC2833
isn't really being used. I've played with adding more debug logging
statements to rtp.c and chan_sip.c to try to catch these frames, but
they don't seem to be there. 

Is there one specific thing I should look for in my debug output or
otherwise, to totally confirm whether or not RFC2833 is being used vs.
inband?