[Asterisk-Users] Noises on ZAP Channels

[Carsten Bock]

Hi everyone,

I have the following annoying problem with my Digium TE410 
Quad-Pri-Card: I sometimes hear strange noises on bridged calls from our 
PBX to the PSTN (a colleage called it "clipping"?)

We have the following setup running:
PSTN <-> Asterisk <-> od PBX
(Trunk one to the PSTN, Trunk two to our existing PBX)

Currently our System does not really do quite a lot, since almost every 
call is currently terminated on the old PBX.
Here comes my zaptel.conf:
span=1,1,0,ccs,hdb3,crc4
span=2,0,0,ccs,hdb3,crc4
bchan=1-15,17-31
dchan=16
bchan=32-46,48-62
dchan=47

loadzone=nl
defaultzone=nl

And my zapata.conf (comments removed)
[channels]
faxdetect=none
language=de
context=default
switchtype=euroisdn
pridialplan=unknown
overlapdial=yes
signalling=pri_cpe
usecallerid=yes
hidecallerid=no
callwaiting=yes
restrictcid=no
usecallingpres=yes
callwaitingcallerid=yes
threewaycalling=yes
transfer=yes
cancallforward=yes
callreturn=yes
echocancel=no
echocancelwhenbridged=no
(we turned the echo-canceling of, because we had problems while 
sending/receiving faxes)
echotraining=yes
rxgain=0.0
txgain=0.0
group=1
callgroup=1
pickupgroup=1
immediate=no
musiconhold=default
signalling = pri_cpe
group = 1
pridialplan=unknown
musiconhold=default
context = incoming
channel => 1-15,17-31
signalling = pri_net
group = 2
pridialplan=local
musiconhold=default
context = from_pbx
channel => 32-46,48-62

In my extensions.conf i use some PHP-AGI Skripts for dialing and 
call-processing.

I hope someone can give me a hint what to do/improve or what to search 
for. So far i did not find anything useful on the net....

Thanks in advance,

Carsten Bock