asterisk users - Nov 2005 - How does DTMF get sent over a PRI in Asterisk

I am trying to trouble shoot some problems with DTMF over PRI. I have a 
digium wct1xxp card and these lines in extensions.conf:

exten => 5556000,1,Record(testtone:gsm)
exten => 5556000,2,Wait(2)
exten => 5556000,3,Playback(testtone)

I called in over the PSTN --to-->  Asterisk. I did a "pri debug",
from
asterisk 1.2.0 console and a few debug lines came up when the call 
connects (but not all the q931 message that should have been there). But 
nothing came up when hitting the dtmf keys. Also when I listen to the 
play back the recorded tones are little more then chirps not long enough 
for a human ear to distinguish tone.

My two question are how does DTMF get send over a PRI (inband? q931 
message?) and how would I go about seeing the duration that was sent to 
me so that I know weather the problem is Asterisk or my telcos!