Strange noise with TDM400P card

Asterisk Asterisk Support
1

Hi to all

We have a strange noise in our phones when people answer our calls.
It’s a metalic noise, like “clack”.
the same happens When other side phones hangs.
We have two cards in our machine. One Digium TDM400D with one module.
We proceed to change the Digium card for other one and we have the same result. Problem persists.

If I connect a analog phone to the line conected to the FXO port of the TDM400P Card all is correct. No “clack”.
We change the telephone cable to discard anormalies and the clack persist.

We are using asterisk 1.4.9 and zaptel-1.4.4
We are running Debian Etch 4.0 with compiles kernel 2.6.18

Our configuration for the digium card is

in zapata.conf

[channels]
language=es
context=from-zaptel
switchtype=national
rxwink=300 ; Atlas seems to use long (250ms) winks
usecallerid=yes
callerid=asreceived
callwaiting=yes
usecallingpres=yes
threewaycalling=yes
transfer=yes
canpark=yes
cancallforward=yes
callreturn=yes
echocancel=64
echotraining=800
immediate=no
rxgain=0.0
txgain=-3.0
immediate=no
busydetect=yes
busycount=8
answeronpolarityswitch=yes
hanguponpolarityswitch=yes
ringtimeout=8000
faxdetect=both
group=0
signalling=fxs_ks
channel => 1

in zaptel.conf

loadzone=es
defaultzone=es
fxsks=1

How could I fix this sound? We just installed many TDM400P cards without this “clack”

Somebody have any idea something about this strange noise (It’s like a clack)

Any clue will be welcomed.
Thanks in advance.

Adolfo Boo

2

Is the clack, a constant repeating noise thats cyclic or irregular?

3

No it’s not cyclic.

It’s only when the call begin, when the people answer the call, and when finish the call

clack—we speak all we wants, a conversation —and when finish, hanging the telephone, clack again. Loud.

The quality of conversation is good. No echoes. Any interferences.

It’s the first time I see this

Thanks for your support