[Asterisk-Users] An anniversary and a lament for FXOs

[Rich Adamson]

> This week marks one year since I first setup an Asterisk server in the
> hopes of transitioning my home office to a total VoIP system. The
> process has been an incredible learning experience. I've tried numerous
> IP hard phones, eventually settling upon the Polycom IP600 as my
> choice. I've also used multiple ATAs including all the Sipura products.
> Using Asterisk has been a challenge, a thrill and (when its working) a
> joy. However, the one thing that I am not satisfied with is the
> performance of the FXO interfaces that bring in my PSTN lines.
> 
> I've tried X100p cards but found them horribly unreliable. I presently
> use Sipura SPA-3000s but they're only marginally better. How is it that
> my Panasonic 4 line SOHO phone system (KX-TG4000B) can have four
> stable, reliable FXOs with no echo at all in a device with a total cost
> of <$500? It seems to me that there ought to be hardware available that
> behaves just as well, but bridges the PSTN to the SIP/IAX domain?
> 
> I've read a lot on the list about how difficult designing FXOs can be,
> but that flies in the face of the fact that every small multi-line
> phone system has them...and without expection those behave better than
> the devices I've been able to try with Asterisk. The Sipura SPA-3000
> has several settings to adjust for line impedance and
> inductive/capacitive line loading....lots of settings, but it provides
> nowhere near the basic performance of one of the lines on the Panasonic
> KSU. It's simply mind boggling.
> 
> So, while I've posted with respect to FXOs previously, I must ask
> again....what FXO interface device can anyone recommend from real
> experience?

I'd have to agree with you 110%; exactly the same issues here over the
past year. I've spent more money on digium cards then you have invested
in your old system, tried the spa3000, and a few other external gateways.
The external gateways are always far better then the digium/spa adapters,
but most of them have other issues that preclude production use. The
market space is absolutely wide open for a two-to-four port pstn adapter
of some sort that actually works.

As I'm sure you've seen over the last six months or so, the digium fxo
cards (drivers) suffer from lots of different problems and no one seems
to really care. As a non-programmer, I'm about to give up on those as
I don't have the skills to attempt fixes, and opening bug reports seem
to be totally ignored. Seems at least some of the issues relate to
interrupt latency and/or pci controller problems with selected motherboards,
however there hasn't been any realistic effort focused on identifying
which boards are acceptable/unacceptable.

Seems rather strange for a company that wants to finance the * project 
through sales of adapters to ignore the problems, but guess that's their
call.

Rich