[asterisk-users] t38 ATA

[Steve Underwood]

On 03/13/2010 02:03 AM, Jeff Brower wrote:
> Steve-
>
>    
>> On 03/13/2010 12:00 AM, Alexandru Oniciuc wrote:
>>      
>>> Hello,
>>>
>>> I need a hand in choosing a small ATA, even with one FXS port, that
>>> should do only fax with T38.
>>>
>>> I’ve tried Grandstream (ht286 model) but the faxes go out without ECM,
>>> even if the Fax machine has ECM enabled.
>>>
>>> Is there anyone that can recommend an ATA that might do the trick?
>>>
>>> Thanks,
>>>
>>> Alex
>>>
>>>        
>> The Grandstreams do T.38 quite well, and they do support ECM. It is
>> probably your service provider which is blocking ECM. Many of them do.
>>      
> I've heard that Grandstream uses TI Telogy DSP devices, which might help explain
> their reliable operation at T.38 data level.  Telogy got started in early 1990s and
> was one of the first outfits to make it big in VoIP.  They were acquired by TI in
> 1998 for about 850m.  During the late 1990s period, Telogy did a lot of work on FoIP,
> including helping to write RFCs, contributions to ITU study groups, etc.
>    
I think you will find Grandstream uses TI silicon, but all their own 
software. T.38 is an awful loose spec, so different implementations tend 
to behave quite differently. The flavour of a Grandstream packet 
exchange doesn't appear to be the same as a Telogy exchange.

Steve