Re: [hylafax-users] Faxing over VOIP?

["Rob Rothberg" <rrothberg@xxxxxxxxx>]

As Lee points out, faxing over VoIP simply isn't ready for prime time.  Sometimes it works, sometimes it doesn't.  If faxing is an important part of your business model, for now it would really be in your best interest to stick with POTS lines.  I'm sending about 20,000 pages a month.  Even if only 1% of my faxes are lost, I'm screwed.  I have a whole Asterisk setup running over VoIP and I'd love to use that for faxes as well, hopefully someday soon the reliability will be there to allow that.

On 11/9/06, Lee Howard <faxguy@xxxxxxxxxxxxxxxx> wrote:

Peter Verhoeven wrote:

>Does anyone have any experience with Hylafax on top of a VOIP line?
>
>I've been testing this succesfully with one line. i.e. take the output
>of one of the modems in hylafax, connect it to a VOIP adapter, and it
>works fine (faxes succesfully transmit).
>
>

Depending on your VoIP adapter and your internet connection and your
VoIP provider your success will vary.  Remember that VoIP connections
are typically lossy due to jitter, and so when you're communicating data
on a lossy medium then data is lost and either will require
retransmission to correct or will cause session failures.  The degree of
lossiness will depend on a lot of things.

>I understand that the proper method for doing this is FOIP and uses
>different protocol than VOIP. So anyone using true FOIP in conjunction
>with Hylafax, I'd certainly be interested in hearing about your setup
>too.
>
>

If your VoIP adapter supports T.38 (FoIP) and if your VoIP provider also
supports T.38, then the adapter probably uses T.38 for faxing already.
It's just a matter of configuring the adapter and getting a compatible
provider.  You probably won't notice a difference from there except that
the lossiness becomes a non-issue.

>The next stage I want to test is 8 simultaneous fax over VOIP lines, and
>I'm wondering if any solutions exists to do this without all the
>hardware layers. i.e . currently it's hylafax->faxboard->voip
>adapter->internet. Is there any way to go hylafax->internet direct?
>

There are two softmodems that work with HylaFAX that I know of.
t38modem from OpenH323 and iaxmodem.  These would let you do that.
However, again, the idea of passing fax audio over lossy VoIP channels
is not entirely a great one.

Lee.


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