[asterisk-users] Asterisk t38modem Fax gateway evaluation

[Steve Underwood]

On 02/18/2010 03:40 PM, DLeese at LStelcom.com wrote:
> Hi,
>
> I am trying to fix a Asterisk setup with buggy (POTS) Fax machines. The
> setup consists of the following components:
>
> - A Digium TE121 for connectiong to E1 ISDN
> - Debian box with Asterisk 1.4
> - Grandstream GXW-4008 SIP ATA to which the Fax machines connect
>
> I am aware of the problems with this type of ISDN<->  Asterisk<->  SIP
> ATA<->  Fax machine installations, e.G. different "clock source" of ISDN
> and the ATA, ethernet timing issues, etc. So it's no suprise that i
> encounter the usual problems: No reliable transmission of faxes, errors
> and aborts with multiple page faxes, ...
>
> Unfortunately the installtion is allready completed and purchasing new
> hardware is not an option. Thus i have come up with the following idea
> und need some small pointer if this is even possible:
>
> remote<=whatever=>  PSTN<=ISDN=>  Digium<-->  Asterisk<-->  t38modem
> <=Ethernet=>  Grandstream<=POTS=>  local
>   FAX                        E1     TE121        1.4
> SIP       GXW-4008            FAX
> machine
> t38
>
> Is it possible to decouple the internal Fax communication from ISDN
> using t38modem or as an alternative "Fax For Asterisk", perhaps in
> conjunction with HylaFAX?
>    
If you are trying to get from the PSTN to a FAX machine on an ATA 
neither Fax for Asterisk or HylaFAX will be of much help. You need a 
T.38 gateway function running in the Asterisk box to talk to the ATA. 
There are patches around for adding that function to Asterisk, but its 
not in the standard distribution.
> I was unable to find any current information about theese subjects on
> the www. Most postings/articles are 4-6 years old and state that it's
> impossible, but this was way before t38modem and "Fax for Asterisk". I
> would be really grateful if anybody could come up with some current
> information, howtows, etc.
>    
4-6 was before Fax for Asterisk, but several options for faxing to and 
from a file, including t38modem, have existed for a long time. Digium 
has just been extremely slow integrating a T.38 gateway function into 
the Asterisk distribution.

Steve