TDM2400E Audio problem

Hi,

I’ve had an asterisk system which uses a TXM2400E running at a customers site for a few months.
This has 2 x FXO modules & 2 x FXS modules.
Software was originally Zaptel 1.2.10 since updated to 1.4.4
It has a couple of analog zap extensions, but mostly Polycom 501 & 601 phones.

I cannot get decent incoming audio quality on the FXO trunk lines (presently six individual lines from British Telecom).

The problem is a ‘gating’ effect on the audio, with quieter sounds being muted. This seems to partly depend on the background noise in the room (at ‘this’ end), if the acoustic noise level is high the gating effect is much worse to the point where only fragments of words are heard.

I have the UK settings in /etc/zaptel.conf:

[code]#

Zaptel Configuration File

This file is parsed by the Zaptel Configurator, ztcfg

loadzone=uk
defaultzone=uk

fxsks=1-8
fxoks=9-16
#[/code]
(I never did figure out how to set the country parameter for the tdm24xxp module in modprobe.conf, so modified the source to set UK as the default rather than ‘FCC’, i.e. static char *opermode = “UK”; )

Initially running fxotune with the standard documented parameters improved things slightly, running it with -i 1 so it actually got a quiet line improved it a bit more; but the echo figures produced still seem poor (I can’t remember the exact displayed values but something like 4 out to 0.8 - 1.0 return).

There is no audible echo on the line, just the gating effect. It’s as if something is muting the incoming audio until it’s louder than some threshold related to the ‘local’ background noise, though it still happens in a quiet room - the background noise from the other end of the conversation cuts in & out.

The incoming audio is also very low level when ungated, I’ve had to put a lot of rxgain on in zapata.conf:

[code][channels]
language=en
cidsignalling=v23
cidstart=polarity
sendcalleridafter=0
busydetect=no
callprogress=no
threewaycalling=yes
transfer=yes
useincomingcalleridonzaptransfer=yes

; Span 1:WCTDM/0 "Wildcard TDM2400E Board 1"
context=from-zaptel
signalling=fxs_ks
faxdetect=incoming
usecallerid=yes
echocancel=yes
callerid=asreceived
echocancelwhenbridged=no
echotraining=800
rxgain=14.0
txgain=8.0
group=0
channel=>1[/code]
(other trunk channels use similar values).

Any help appreciated,
Robert Jenkins.