[Asterisk-Users] Eicon ISDN to Voicemail audio dropouts

[Dave Karr]

Hello,

I'm having a problem with significant audio dropouts occurring in voicemail 
messages left via an ISDN-BRI trunk.  Dropout durations are as short as 
15ms and as long as 200-300ms.  The audio that is recorded, appears to be 
otherwise complete, just with frequent holes punched in it.

The same trunk has no problems with audio files played toward it from 
voicemail, nor interacting with other trunk and station ports on the same 
system.  The only identifiable problem with audio dropouts is ISDN -> 
Voicemail.

Redhat 9.0  SMP
Asterisk version is from CVS -r v1-0
ISDN trunk card is a 4 port Eicon BRI and I'm using the Eicon 7.5 CAPI 
drivers compiled on the same machine.
Using chan_capi 0.3.5
The machine also contains two Digium TDM400P cards.  One has 4 FXS modules, 
one has 2 FXO modules.
Computer is a HP Netserver E800 with 2  PIII 833MHz CPU's.  256M Ram.

Location is U.S. and central office is a DMS100.  The Eicon is configured 
for NI-1, DMS100.

Again, calls can be placed between all interfaces in any combination and 
there are no audio dropouts other than the ISDN -> voicemail path.

I've tried different voicemail recording formats (i.e. gsm, wav, etc.) and 
limiting the recordings to just one file.

I've not dug to deep into the source code yet, and was hoping someone might 
point out where the audio path differences start to occur with regard to a 
call between the CAPI interface and another zaptel interface, and when the 
CAPI interface is routed towards voicemail.

It seems odd that the recorded audio has these periods of silence injected 
in it, rather than the lost audio also resulting in lost time (so to speak).

I've got a strong background in both telcom and embedded software/hardware 
development, and am willing to troubleshoot this... just looking for some 
pointers on where to start such as to where the problem most likely lies to 
avoid covering old ground.

Thanks,


--Dave