[Asterisk-Users] least sucky FXO interface?

[Rich Adamson]

> Would anyone care to offer opinions as to the FXO interface which sucks
> the least :)  I have an application in which it appears I must route
> certain calls out an analog PSTN line.  Presently, I am testing an 
> SPA-3000, but I can't seem to get the echo heard on the IP end of the
> call down to a non-annoying level.
> 
> Any suggestions welcomed :)

There's likely to be as many opinions on that as there are list readers.
So, here's my 15 months of actual hands-on experience to date. :)
- X100P cards: sort of okay in North America, but not so cool in any
  country that uses different telco standards. (Yes, there are several
  exceptions.) In NA, the code supporting the X100P is basically the
  same code that supports the TDM card. (eg, if you have a problem with
  one, you are very likely going to have the same problem with the other
  "in NA".)
- TDM card: not all that bad at all. Still needs some help, but I'd
  suggest that a large percentage of negative postings is a reflection
  of the implementors ability to understand and address the issues, and
  not the card itself. (Yes, there are several exceptions here too.)
  Both the X100P and the TDM card are sensitive to what seem to be
  motherboard issues with pci bus and/or interrupt latency.
- SPA3000: Not a lot different in terms of usability issues when
  compared to the TDM card. Some folks have echo issues with it while
  some don't. Some have complained about early failures, others not.
  Very sophisticated in terms of programability; more options that what
  most folks even begin to understand. (The last two/three software
  upgrades have improved the documented echo issues, but not totally.)
- Mediatrix 1204 gateway: worked well, no echo, etc. But, that box does
  not conform to several sip standards and there is no real support for
  it other then from the company you bought it from. Mediatrix as a 
  company seems to be in a financial bind and they've choosen not to
  support it directly, there is no guarantee that any problem will ever
  be addressed, and the mechanism required to make it play with * is
  very non-standard. There are no free upgrades; each upgrade is suppose
  to be chargable to the customer.
- IAXy: I've not played with these, but reading the archives will point
  out various issues in certain environments. (E.g., no dns support,
  nat issues, few codecs supported.)

The market for one-to-four fxo interfaces is rather immature and lacking
overall. Those boxes that are reasonably priced seem to have issues of
one sort or another, while the more expensive ones tend to have fewer
issues but also fewer people using them (and documenting their concerns).
So, is the lack of noise from the expensive ones really the result of
a better implementation, or is it related to those cards have not been
exposed to the negative situations that cheaper implementations have
seen? No idea personally. (Not even going to comment on the T1 cards
and muxes as they don't apply in the small 1-to-4 fxo shops.)

Rich