[Freeswitch-users] [Out of curiosity] Why not use a voice modem for FXO?

[Steve Underwood]

On 05/27/2010 04:26 AM, GillesToo wrote:
>
> Anthony Minessale wrote:
>    
>> Even if you get it working the reward is not worth the effort. You would
>> experience a lot of echo and other problems
>>      
> I read somewhere that the reason for those problems people often have with
> X100P cards (such as echo or bad far-end disconnect supervision) is that
> most of them have they use the Silicon Labs DAA chips Si3012/Si3035 which is
> only good for use in countries that use the FCC standard; Countries that use
> the CTR21 standard (Europe, and others) require the Si3014/Si3034 chips,
> which support global line standards.
>    
Most X100P clones don't use any kind of Silicon Labs chip. Whatever chip 
they do use will probably not be programmed properly to match the line, 
because the drivers don't support that. However, with the use of a 
decent echo canceller you'll probably never notice. Use OSLEC with most 
X100P cards on most lines around the world and the results should be 
pretty good. The only things those X100P cards can't do, which some more 
complex FXO cards can, is detect line current breaks and reversals. Most 
lines around the world don't produce breaks or reversals so its not a 
major issue. Everything else is down to what the host software does.
> Anthony Minessale wrote:
>    
>> ... and the time you spent working on it would be better spent doing
>> something more meaningful and using the money you received to buy a real
>> TDM card or better still, a FXO->SIP ATA.
>>      
> I thought TDM cards were a better solution to connect an IP PBX to a
> landline. Why would you recommend an FXO-SIP ATA instead? And which
> brand/model of ATA is recommended for use with Freeswitch?
>    

Steve