[Asterisk-Users] * fax reliability between ISDN PRI and FXS ports

[Rich Adamson]

> I am building for a customer an * solution that will use 2 Digium cards.
>  
> 1 x TE110P (T1 ISDN PRI)
> 1 x TDM40B (4 analog ports, 2 for faxes, 2 for extensions)
>   
> The system will be connected to the PSTN through the T1 ISDN PRI interface.  All customer 
extensions will be SIP phones except 2 fax
> machines that will use the analog FXS ports on the TDM40B card.
>  
> I have been investigating on this list and found that faxing is not reliable between Zaptel 
cards and that Digium does not support nor
> recommend fax over the TDMXXB interfaces.
>  
> Is this true ?  Will fax not be reliable enough for my customer ?

True... the TDM card (or its drivers) has an issue with missed frames
that seriously impacts its ability to handle _any_ modem-type calls.

> Will it be better to use Audiocodes digital and analog gateway (ATA) 
> with T.38 capabilities ? 

A good ATA should work fine, but you should probably test it before
exposing your customer to potential problems. Others have used ATA's
with analog fax machines.