[Asterisk-Users] X100P problems / UK Supplier of TDM400P FXO cards

[Mark Bingham]

This didn't seem to appear on the list, so I'll try again. Apologies if
this is a repeat post.

Hi everyone,

I wonder if anyone (esp. UK-based) could help us with the following
(skip to the last paragraph if you don't want the detail!):-

We have been trying to get an Asterisk-based VoIP server set up for our
(small) office. We have two incoming analogue lines and two phones - one
analogue and one multi-handset DECT. We also want to be able to
send/receive calls over SIP to X-Lite.

We have got a machine with Asterisk installed and SIP <-> SIP calls are
working fine. However, we need to be able to access the two incoming
analogue lines. We bought two X100P s and two GrandStream HandyTone
286s. Calls from the two POTS phones seem to be fine to SIP phones, but
calls between the outside world and either the POTS phones or SIP phones
are terrible. Initially we had dreadful echo, we have used 128 taps of
echo cancellation and the echo is somewhat better (although it is still
dreadful for the first 10-20s of the call). However, we now get quite a
lot of "breaking up" while the person on the SIP phone / our analogue
phone is talking.

I believe the cause of this is the X100P - in particular, the impedance.
As far as I can tell, in the UK, the lines are Zcomplex (2) = 230 nF //
1050 ohms + 320 ohms. The X100P seems to only be able to produce the US
impedance = 600 ohms. As far as I can find out, the Digium TDM400P with
FXO modules would not have this problem, as it has a software-adjustable
impedance. However, I have not been able to find a supplier in the UK of
the FXO modules for the TDM400P.

So, this is where you might be able to help!
*	Have you used X100P cards in the UK successfully?
*	Do you know a supplier of TDM400P cards in the UK?

Thanks

Mark

-- 
Mark Bingham
Technical Director
Tamsin Limited
Business and Technology Centre
Bessemer Drive
Stevenage
SG1 2DX

Tel. Office: 01438 791079
Tel. Mobile: 07977177720