asterisk users - May 2006 - Digium TDM400P vs Sangoma A200 for 2 x FXO

Evening all.

I'm looking at building an Asterisk system for one
of the projects of the Charity where I'm the
SysAdmin.

The project has two analogue phone lines - BT
Featureline Compact, we're in the UK - that I'd
like Asterisk to handle.

My current quandary is which FXO interface to use.
I've been looking at the Digium TDM400P and
Sangoma A200, which are similar prices for two FXO
lines. Can anyone comment on the relative merits
of those two devices? Are there any other options
in the same price range?

As we're a small Charity, price is a major
consideration. I don't think we can afford the
A200's hardware echo-canceller, for instance.

Thanks for your help.

Nick.

-- 
Nick Chalk ................. once a Radio Designer
 Confidence is failing to understand the problem.

Nick Chalk wrote:
>Evening all.
>
>I'm looking at building an Asterisk system for one
>of the projects of the Charity where I'm the
>SysAdmin.
>
>The project has two analogue phone lines - BT
>Featureline Compact, we're in the UK - that I'd
>like Asterisk to handle.
>
>My current quandary is which FXO interface to use.
>I've been looking at the Digium TDM400P and
>Sangoma A200, which are similar prices for two FXO
>lines. Can anyone comment on the relative merits
>of those two devices? Are there any other options
>in the same price range?
>
>As we're a small Charity, price is a major
>consideration. I don't think we can afford the
>A200's hardware echo-canceller, for instance.
>
>Thanks for your help.
>
>Nick.
>
>  
>
Nick:

If you aren't going for the echo cancellation, then I think either card 
will do fine.We have over twenty five systems deployed in rural eastern 
North Carolina locations with six analog lines each and the majority 
work fine with TDM400s, though we have had to replace several with 
Sangoma A200 with echo cancellation to eliminate echo. We are now 
deploying only the A200 because we never know if echo will be an issue 
or if it can be "tuned" away and it is just easier for support to not 
have that worry.

Mike Clark

Though many will probably disagree, you will be LOTS better off with the 
Sangoma A200
It is MUCH more forgiving regarding Motherboards and the PCI 2.2 
requirement, even though the software installation instructions leave 
much to be desired for the inexperienced, it does work, and Sangoma  
fixed a problem I discovered with their FXS module software.
My first experience with Digium and the TDM400 was, when it couldn't be 
seen in a motherboard that said it was PCI 2.2,  Digium's response was 
"try another motherboard"

John Novack


Nick Chalk wrote:
>Evening all.
>
>I'm looking at building an Asterisk system for one
>of the projects of the Charity where I'm the
>SysAdmin.
>
>The project has two analogue phone lines - BT
>Featureline Compact, we're in the UK - that I'd
>like Asterisk to handle.
>
>My current quandary is which FXO interface to use.
>I've been looking at the Digium TDM400P and
>Sangoma A200, which are similar prices for two FXO
>lines. Can anyone comment on the relative merits
>of those two devices? Are there any other options
>in the same price range?
>
>As we're a small Charity, price is a major
>consideration. I don't think we can afford the
>A200's hardware echo-canceller, for instance.
>
>Thanks for your help.
>
>Nick.
>
>  
>

I've no experience with the A200, so I can't really pass judgement on
it. We
have 2 sites with TDM400P cards currently deployed (one with 3 FXO, the
other with 1 FXO and 3 FXS). The site in Northampton with 3 FXO has been an
absolute nightmare over the last 9 months the system's been in place.
Initially we had big problems with echo that no amount of tweaking of the
echo parameters would fix.

Once asterisk 1.2 was deployed, things improved remarkably. I took the time
on-site to properly configure the txgain and rxgain using a milliwatt tone
coming from one of our other servers in a datacentre (rather than relying on
using ztmonitor -v whilst the client was making/receiving calls - you can't
guarantee whether the party they're talking to has *their* gains properly
configured, which means you end up with completely different results on
every call). Once I'd got the gains properly configured, fairly standard
echo cancellation settings of "on" and "echotraining=800"
seem to work
relatively well.

One thing worth checking with BT - if you can find someone who can give you
an accurate answer - is whether the Featureline will give you disconnect
supervision. If it will, so much the better, as * 1.2 seems to have usable
support for it. If it works reliably, you can increase the number of busy
tones to detect before a channel is killed (this will massively reduce
incidences of false hangups).

It's still not as good as the building next door where they have 2 ISDN
BRIs, but it works, and I've not had any complaints for the last month since
their box was upgraded to 1.2.

Hope that helps.

(shameless plug - I have a spare TDM400 card here if you're looking to
acquire one at a reduced price - discuss off-list if interested)

Regards,

Chris
-- 
C.M. Bagnall, Director, Minotaur I.T. Limited
This email is made from 100% recycled electrons