[Asterisk-Users] chan_capi broken incoming audio

[Vic Cross]

G'day all,

I've been googling myself silly looking for help on this one but have come 
up blank.

I have an AVM Fritz!Card PCI, and I'm using chan_capi v 0.3.1 with * from
CVS-HEAD-05/08/04-22:48:00.  I can start * and make and receive calls on
ISDN fine but after a few hours of * uptime, on any ISDN call I make or
receive from my SIP handsets (7960 or ATA-186) I get bad audio: on the
ATA-186 I get either no audio incoming from ISDN at all (I get a scratch
of sound every 2-2.5 seconds or so, but otherwise nothing) or robotic
stuttering sound.  On the 7960 the problem is just the no-audio-at-all.  
On either, outgoing audio (sound going out to ISDN) is fine.

Originally I thought the problem was *all* ISDN calls, so I was debugging
chan_capi.  I have a couple of analogue handsets attached to a TDM400P 
though, and tried a call through that: perfect.  I can receive a call on 
the 7960 receiving no audio, transfer it to the TDM phone and get perfect 
audio, transfer it to the ATA and get bad/no audio.

The last idea I came up with was a WAG to do with codecs - my phones all
used ulaw and my ISDN will be using alaw; even though * would have 
transcoded I thought it would work better if I switched the phones to 
alaw...  As expected, no difference (I really didn't expect it to make a 
difference).

To me, it looks like a variation of the SIP RTP timestamp problem (yes, my
7960 is at 6.3 code), but the problem exists on the ATA-186 too and I
don't have any other issues with that (not even SIP-IAX, where the 7960 is
really bad).  Also strange is that there is no problem at all on my X-Lite
softphone; I did the same thing transferring a call back and forth from
X-Lite to the 7960 as I did with the analogue handset above.

I guess this is going to come down to the old "crawl over the ethereal 
dump with a microscope" kind of thing, but I'm hoping that someone out 
there has solved this issue before.  I know there's plenty of chan_capi 
users with ISDN BRI via a Fritz!Card, maybe somebody has had a similar 
problem and can help?  Please?

Happy to try and produce traces etc for diagnosis.

Cheers,
Vic Cross