Re: [hylafax-users] USR are buggy modems?

[Lee Howard <faxguy@xxxxxxxxxxxxxxxx>]

Bojan Stojanovic wrote:

> Hello everybody,
>
> Should I really avoid buying USR modems?
> They are most common external modems in Sebia and Montenegro market.
>
> Other alternatives that I have are Agere, SWEEX and Prolink external
> serial modems.
>
> http://www.hylafax.org/content/Handbook:Basic_Server_Configuration:Choosing_a_Modem
>
> "Also in the functional-but-buggy category are USR/3Com modems; they
> tend to work better in Class 1 than in Class 2.0, but it still isn't
> ideal. (USR doesn't seem to be fixing these things, either.) If you use
> one of these modems and experience problems do not be surprised to learn
> that it is an issue with the modem itself."

Although you're going to hear some people tell you that USR modems work 
perfectly for them the answer is - yes - USR modems have some problems 
in fax modes.

In Class 2.0 they have a lot more problems than in Class 1.  Many people 
have been able to use USR modems in Class 1 and tolerate whatever 
problems they have from there.  Recent insight into some of the USR bugs 
have enabled us to suggest configurations that should hopefully minimize 
the appearance of the remaining Class 1 bugs.

So although I do not recommend USR modems, and I would never choose to 
purchase one, myself, I do not refuse to work with them if my customers 
have them already.

The remaining Class 1 bugs are these:

 +FRS and possibly +FTS sometimes trigger modem resets in the middle of 
a call... and at that it's doubtful that +FRS/+FTS even work at all.  
Without being able to use these HylaFAX must use software pauses instead 
of asking the modem to detect or transmit silence.  And since it is the 
modem that actually hears the audio on the wire HylaFAX must rely on the 
modem for accurate measurements in silence detection and transmission.  
By using software pauses instead of +FRS/+FTS there is a greater risk of 
losing synchronization between the sender and receiver.

 The modem does not report +FCERROR as it should.  For the most part 
this means that if the remote fax sender transmits a V.21 message signal 
at an unexpected time that it becomes much more difficult, if not 
impossible, to switch gears and get it... and this also can lead to a 
synchronization loss.

Lee.

____________________ HylaFAX(tm) Users Mailing List _______________________
 To subscribe/unsubscribe, click http://lists.hylafax.org/cgi-bin/lsg2.cgi
On UNIX: mail -s unsubscribe hylafax-users-request@xxxxxxxxxxx < /dev/null
 *To learn about commercial HylaFAX(tm) support, mail sales@xxxxxxxxx*