Re: [hylafax-users] [hylafax-devel] Re: [Bug 859] New: Adaptive answer using +FCLASS=8

["Luke McKee" <hojuruku@xxxxxxxxx>]

Lee,


On 25/04/07, Lee Howard <faxguy@xxxxxxxxxxxxxxxx> wrote:
> Luke McKee wrote:
>
> > Modems are obsolete
>
>
> > So nobody needs voice modems.
>
>
> Well, if this were a debate then I would contend that your own use of a
> voice modem would be a perfect argument against these two statements.
> But since it's not a debate.... ;-) I'll not again say that the PSTN is
> far from dead.
Once upon a time when I was young I ran a 4 line BBS multitasking
under Dos with DesqView...
For people who live in backwards countries who didn't jump on the ISDN
bandwagon modems have their uses. Voice modems due to their
differences in data format, flow control and lack of full low latency
full duplex voice comms mean the voice part isn't worth paying more
than $10 for when you can get other devices that do perfect voice
handling with pabx's.

I kind of feel stupid arguing so much because I *plug* picked up a
X100P I ordered yesterday from the post office. Making my modem
completely redundant for answering the phone.

I only played with my voice modem because I didn't have the gear to
get asterisk going properly on the PSTN and I wanted to play with
VOIP. So in the meantime I set me up a TAM (Telephone answering
machine), thinking it would be a good backup if my PABX crashed down
the track. So the whole time I wasn't really going to be using this in
production.

When I saw a commercial entity doing Microsoft style FUD tactics and
taking a interest in the suggestion because it would improve the low
cost alternatives support in hylafax. This has motivated me even more
to make the patch. The more I thought about how to implement the patch
the less daunting it has become.

> > 14.4K is the maximum carrier speed over a 64kbit codec.
>
>
> This isn't true.  This should be obvious simply by knowing that on
> typical analogue PSTN links the digitized form of that data is alaw or
> uLaw (8000 Hz sampling, 64 Kbit codec) and that you can easily set up
> your own V.34 (33.6 Kbps) connection between two analogue-connected
> modems.  Should further evidence be needed you can take special
> precautions to ensure a jitter-less VoIP connection and use two solid
> ATAs to pass SIP uLaw/alaw data between two V.34-Fax-capable modems and
> you should be able to get V.34 connections there that are faster than
> 14.4 Kbps.

A ISDN channel is a 64k PCM link right. It's low latency because it's
a switched circuit.
You should know that with packet loss and re-ordering over the
internet you'd be lucky to get anything to get a 33.6 carrier.
Iaxmodem hardly copes over a LAN - it's a network application that
should only be used on the loop back port. ISDN due to it's "routing"
method doesn't have this problem.

Instead of buying mainpine or other 33.6k support V.34 modem board I
might also want to add that any active or passive ISDN card , such as
a fritz pci will also do 33.6 k PCM faxes. I've got one here and I'll
be firing it up again after 5 years offline.
If you use it for outbound calls and you get the same ISDN call rates
as for analogue PSTN where you live then the odds are the digital
channel will go right up to the exchange of the call receiver, or at
least one less hop over analogue, so you'll have a perfect quality
lossless PCM 64 link to send V.34 faxes.

I take it most of the professional high volume hylafax sites would use
active ISDN boards over modems for fax right?

And that's just fax. If your a small business and you want to do voice
properly and not buy any other fax cards, ISDN will allow you to use
your trunks for both voice and fax reception saving you money.

(fritz passive use the host's CPU to send faxes - but active ISDN does
that processing onboard)

With broadband taking off there many digital ways of sending faxes
(ISDN, VOIP@xxxx, T.31 email fax relay,T.38 fax relay) and most people
except home users who send large amount of faxes would be worth
looking into them and their costs structures before asking your telco
to give you extra lines with extra rentals just to send lots of faxes.

Cheers,

Luke McKee

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