[asterisk-users] Dialplan checkup

[Robert Jenkins]

Hi,
As far as I understand,
Fax detection works by the fax machine sending a specific tone down the
line.

Until the phone has been answered, there is no audio path so the receiving
end cannot know what type of call it is.

The stand-alone fax switch devices that appear from the calling end to work
without answering actually answer the call then, if it's not a fax call,
generate the ring signal for the phone themselves.

The way it works with a Fax machine designed to work with a separate
answering machine is either:
The fax has an internal 'fax switch' function that generates a ring to the
external device, or

the fax waits for the answering machine to pick up the line, then 'snoops'
the audio for the fax identification tony and takes over the call if it
detects it.

Either way, you cannot determine if it's a fax call without answering it.


If your machine has a 'through' phone outlet for an answering machine (and
the fax uses the snooping method of fax detection), you should be able to
use this for the Asterisk trunk and as long as the Asterisk box *always*
answers at some point, either via someone receiving the call or voicemail /
IVR kicking in.

Once the call is answered, the fax would be able to detect any tone on the
line and take over if required, dropping the line out to the asterisk
system.


Robert Jenkins.


> -----Original Message-----
> From: asterisk-users-bounces at lists.digium.com 
> [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of 
> Barry Fawthrop
> Sent: 10 February 2007 02:49
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: Re: [asterisk-users] Dialplan checkup
> 
> Thanks Guys
> 
> I already have the fax machine a brother all-in-one Printer, 
> scanner, fax.
> I realize the s,3, answers the line
> But How can I get s,2, to detect if it is a fax and take it 
> from there without answering?
> 
> Or can someone explain what make an incoming goto  exten => 
> s,..........
>                             and what make it go to exten => 
> fax,........
> How does this logic work??
> 
> Thanks again
> 
> Barry
> 
> Barry Fawthrop wrote:
> > Hi All
> >
> > Curious will this work
> > Std. PSTN line  ---x------ X100p
> >                   |
> >                   ------ Fax Machine
> > Using a standard "home phone" pstn line with a splitter 
> connecting a 
> > fax machine and X100 Asterisk Box Incoming Line: Can I have in the 
> > dial Plan [incoming] exten  => s,1,Wait(1) exten  => s,2,IfFax 
> > continue to ring, so that the Fax Machine gets it exten  => 
> s,3,Answer 
> > exten  => s,4,Playback(Message) exten  => 
> > s,5,Dial(SIP/1000&SIP/2000&SIP/3000)
> > exten  => s,6,Hangup()
> > exten  => fax,1,Wait(30)
> > exten  => fax,2,Wait(10)
> > exten  => fax,3,Hangup()
> >                 I'm wanting the line to ring, If it is a 
> fax coming in 
> > then Asterisk leaves the line alone and lets the fax machine handle 
> > the call. If it is a call then Asterisk answers, plays a 
> greeting and 
> > rings the IP phones?
> >
> > Question is how does asterisk detect the call without answering?
> > I'm not wanting Asterisk to handle the call if it is a fax 
> if possible???
> >
> > I look forward to your input,
> > Thank You
> >
> > Barry
> 
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