[Asterisk-Users] Re: Connection TDM400P to UK PSTN

[Chris Bagnall]

> Successfully got the adapters to allow the BT phones to ring 
> on lines coming out of a TDM.......... but now my latest 
> problem is echo.
> Suggestions / Experiences in UK appreciated

Most of our clients with BT lines tend to have ISDN BRIs, but we do have one
in Northampton running 3 analogue lines from a TDM400.

zaptel.conf is as follows:
fxsks       = 1-3
loadzone    = uk
defaultzone = uk

The TDM driver is loaded with opermode=UK and the output from dmesg confirms
this.

Relevant settings from zapata.conf are as follows:
echocancel=yes
echocancelwhenbridged=yes
echotraining=800
rxgain=8.0
txgain=-4.0
busydetect=yes
group   = 1
context = inbound
channel => 1-2
group   = 2
context = inbound
channel => 3

They're running Asterisk/Zaptel 1.0.10. There were major echo issues when we
first deployed the system back in September, but some careful tweaking of
rxgain and txgain seems to have largely resolved the situation. Certainly my
experience has been that rxgain and txgain have far more impact on echo
reduction than any of the echo-specific settings. Get the gains right first,
then play with the echo-specific settings.

Regards,

Chris
-- 
C.M. Bagnall, Director, Minotaur I.T. Limited
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