[Asterisk-Users] Which is the best fax-modem for testing ?

Steve Underwood steveu at coppice.org
Sun May 21 01:56:20 MST 2006


Lee Howard wrote:

> Olivier Krief wrote:
>
>> For example, it seems that Brother 8360P uses Super G3 mode.
>> Is there a fax-modem offering such capability so that I could easily 
>> check if I still cannot  hangup when I enable or disable Super G3 mode ?
>
>
>
> MultiTech 5634-series and MainPine RockForce fax modems (Agere 
> chipset) support SuperG3.  You'd run these with HylaFAX, for example, 
> and not Asterisk.

It is worth pointing out that the V.34 modems have almost no chance of 
achieving V.34 speeds if you go:

        PSTN->analogue line->asterisk->FXS port->modem

if you go

        PSTN->digital line->asterisk->FXS port->modem

performance will depend on the FXS port, and any internal timing issues. 
With a TDM400 card its fairly unlikely to work. With a channel bank 
connected to a port on the same digital card that connects to the PSTN 
chances are high.

The problem with the PSTN->analogue line->asterisk->FXS port->modem path 
is signal degradation through the extra analogue->digital->analogue step 
is too much for V.34. For FAX modems up to V.29 it is no problem. For 
V.17 is tends to work if the port quality is good.

Steve





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