[asterisk-dev] garbled audio

[Sam Liddicott]

Please could experts see if this message triggers any memories:

On the usbb2k channel I'm modifying to provides PSTN in/out; with this 
extension definition:

exten => incoming,1,Answer()
exten => incoming,n(exten),Playback(vm-enter-num-to-call)
; NOTE: extra goodbye for testing
exten => incoming,n(goodbye),Playback(vm-goodbye)
exten => incoming,n,WaitExten(5)
exten => incoming,n(goodbye),Playback(vm-goodbye)

dialing gives clear audio for the first two messages and garbled audio 
for the final message. WaitExten -even if it recieves no DTMF seems to 
cause the next message to be garbled.

Further, on a fresh asterisk startup, incoming calls from the PSTN hear 
garbled messages which just about sound like they should.

But if I dial out on the usbb2k, no 41, with this extension:
exten => 41,1,Dial(USBB3G/s)
I get a PSTN dial tone and if I then hang up and THEN if I dial incoming 
from that PSTN I get clear audio up until the WaitExten ....

If I dial a valid extension number during WaitExten, I get connected and 
connect audio is clear.

It is only if WaitExten times out and I progress that I get garbled 
audio (on the PSTN).

NOTE: Even thought the PSTN audio (as heard on the PSTN) is garbled, the 
incoming DTMF from the PSTN is decoded fine.

If someone has a clue about what could cause such predictable garbling 
(and temporary un-garbling by using the out-channel) I would be very 
grateful...

Sam