Re: [hylafax-users] some serious modem testing

[Lee Howard <faxguy@xxxxxxxxxxxxxxxx>]

Bojan Stojanovic wrote:

> I got some modems, and they work in Class 1 (I managed to send and
> receive some faxes). But how can I be 99% sure that they will work
> reliable when I put server in regular every day use?

When a manufacturer sends me a new modem to test I deliberately do lots 
of, perhaps uncommon, fax things with it in order to provoke errors.  
There's a lot more of this to test with a Class 2/2.0/2.1 implementation 
than there is to test with Class 1/1.0.

In Class 2x I send and receive faxes of varying formats and at different 
modulations and speeds (I test it against a Class 1 modem on the other 
end, since I can control things much better in Class 1)... and I examine 
the logs and resulting fax images and compare them against T.32 and T.30 
specs.  This requires a lot of faxing back and forth to do.

In Class 1x you can test virtually everything that the Class 1x 
implementation does in a single call.  To test the DSP you'd want to 
test one fax reception and one fax sending for every modulation 
supported.  Then I examine those logs and resulting fax images and 
compare them against T.31 and T.30 specs.

But as most people aren't going to know T.30/T.31 well enough to see the 
issues just by looking at the logs, probably the best thing that you 
could do to test modems in Class 1/1.0 is to have two modems hooked up 
and send numerous faxes between them and expect no errors to occur at 
all.  If you do get errors then resolve those issues before being 99% 
sure that they will work reliably in production use.

Thanks,

Lee.


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