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

[Steve Underwood]

Olivier Krief wrote:

> 2006/5/21, Steve Underwood <steveu at coppice.org 
> <mailto:steveu at coppice.org>>:
>
>     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
>
> Hi Steve,
>
> Which fax-modem would you pick to highlight this behaviour ?
> I mean :
>
> "If you had to buy a single fax-modem to complement a laptop to 
> demonstrate a TDM or ToIP system is V.34 or V.17-capable, which 
> fax-modem would you choose ?"
>
> You launch a shell-script from your laptop and it sends 5 or 6 faxes 
> with the same content to a given destination (always the same one) at 
> different speeds or protocols.
>
> Reading destination fax machine's reception report, you can rate each 
> sending and tell
>  what your System Under Test is capable of.

I thought I had clearly said this was related to the nature of the path, 
and has little to do with the specific modem you use.

Steve