asterisk users - Feb 2004 - asterisk and fax over ip - concept

I will be using Asterisk to connect remote offices to PSTN - over IP (SIP).
These offices will use fxs gateways such as madiatrix and audiocodes to send
VoIP traffic to Asterisk. Asterisk will in turn push their traffic to PSTN.
The other way round will also work ie. Asterisk will forwards traffic from
PSTN to those gateways (offices).

The problem that I have though is that most companies send and recive
faxes - and so will these. I dont want these offices to bypass faxes
directly to PSTN but would somehow like to workaround fax over ip and
Asterisk.

What came to my mind was to add an fxo gateway (connected to PSTN) beside
Asterisk to break out faxes to PSTN. Such a fxo gateway could communicate
with the fxs gateways at customer premises and could reliably transmit faxes
using t.38. The way I would imagine it is as such. When Asterisk would see a
'call' coming from a specified number (assigned to a sip port of an fxs
gateway) instead of bridging the call directly to PSTN over a zap interface
the 'call' coule be forwarded to the fxo gateway (over sip) that could
reliably handle the 'call' (fax transmission).

Would the t.38 transmission be properly handled by the t.38 supporting end
points whith mediastrem passing through Asterisk ? (dont have much
experience with t.38) Has anyone ever tried anything similar / different /
wierder to try and deal with fax over ip and Asterisk ? Any suggestions and
comments are welcome.

Regards,

Dave

On Mon, Feb 09, 2004 at 02:28:02PM +0100, Dawid Mielnik
wrote:
> 
> Would the t.38 transmission be properly handled by the t.38 supporting end
> points whith mediastrem passing through Asterisk ? (dont have much
> experience with t.38) Has anyone ever tried anything similar / different /
> wierder to try and deal with fax over ip and Asterisk ? Any suggestions and
> comments are welcome.
What I would do i this situation is work out a fax <--> email 
gateway. Best case this could be done entirely with software
on the asterisk box, worst case a faxmodem hairpinned into an
fxs card using hylafax. Instead of a fax machine, the people
could have a scanner, and they would send their fax as an
email attachment. Likewise recieved faxes could be sent directly
to a printer, or to an email address, or even stored and made
accessible on a webserver...

Cheers,
-w
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Hi!
> What I would do i this situation is work out a fax <--> email
gateway.
> Best case this could be done entirely with software on the asterisk
> box, worst case a faxmodem hairpinned into an fxs card using hylafax. 
Why exactly would hylafax be a "worst case" solution only, why would
you
tink that that the Asterisk solution is better at all?
>  Instead of a fax machine, the people could have a scanner 
Hmpf... I've always found that to be a very bad replacement for an analog 
fax, at least as soon as you have to deal with more than 1 page. Plain 
old analog fax machines are a very well designed devices... ok, for 
receiving faxes some unified messaging or e-mail attachment is fine, on 
that part I can agree.

Cheers, Philipp

Would the following be a doable solution:

1. An Asterisk-box on site with FXS
2. Plug Fax into FXS
3. User uses facsimile machine to call a number - Asterisk answers
4. Stores called number into variable ${FAXDESTINATION}
5. Use RcfFax of * to store fax within asterisk
6. mail stored fax together with ${FAXDESTINATION} off to central office 
with outgoing PSTN?

No PSTN line needed, user does not need to change his/her way of doing 
things.

If you want to provide feedback with regards of fax success, prefix the 
phonenumber with a 3 letter account number specifying the sender to be 
used for later eMail notification.

Just a thought.

rgds
pos