Re: [hylafax-users] HDLC frame not byte-oriented

[Lee Howard <faxguy@xxxxxxxxxxxxxxxx>]

Andrew Rinaldi wrote:
> If you changed from a USR to a Venus (this is important) based MultiTech and
> had no improvement then you need to look elsewhere for your issue.  Once
> this issue is resolved you will be glad that you have the Venus chipset.

In my opinion the missing Class 1 features of +FCERROR support and 
proper +FRS/+FTS support make the USR a no-go on any high-volume 
production server.  Those features, properly implemented as on the 
Lucent/Agere Venus and the Agere/LSI CFAX34 ... as well as on many 
Rockwell/Conexant [hardware] chipsets... make them far more valuable for 
reliable Class 1 faxing.

The V.34-Fax support on the Venus and CFAX34 make it particularly 
attractive.

On the later Rockwell and all Conexant chipsets (again, I'm not talking 
about winmodem/linmodems here) there is also support for +FAR=1 which 
makes unexpected signal handling particularly easy, and is a nicety not 
on the Agere/LSI chipsets... however, its behavior can be closely 
approximated through use of the supported +FCERROR indication/result 
where +FAR=1 is not supported.  The nicer thing about +FAR=1 is that it 
indicates that the chipset manufacturer was conscientious about V.21 
HDLC detection... and it gives credibility to a "CONNECT" after AT+FRH=3 
(which should *only* ever mean that V.21 HDLC was detected... not just 
any noise).  Thus we don't see the need for Class1HasRHConnectBug on 
those Rockwell/Conexant modems as we do with Agere/LSI.

In any case, the USR modems have been among the poorest-performing that 
I've worked with.  The biggest problem, I believe, is that USR/3Com has, 
to my knowledge, not worked openly with fax application developers and 
their users to make things better.  Their fax development is a slow, 
slow process.  Most of what you see in their fax modem features (and 
many of the bugs) existed ten years ago in the TI chipset that became 
the basis for their fax modems.

Thanks,

Lee.


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