As it stands now we're at about 99.714% accuracy. Very little with fax 
transmission is guaranteed 100% but it would be nice to get even closer. Due to 
the nature of the detection mechanism if there isn't a valid CNG then the call 
will be assumed voice. There is nothing we can do about that. Perhaps what I am 
looking for is challenging but considering my expectations far from 
unattainable. It should not be impossible to detect the 1100hz CNG tone, it 
should not be any different than detecting the combination of DTMF tones (which 
I believe are combinations of 697hz,770hz,852hz,941hz plus any of 
1209hz,1336hz,1477hz, and 1633hz depending on the keypress). It should be 
easier considering there is a standard length for the CNG tone whereas with 
DTMF on many phones it depends on how long they feel like holding the button 
down.

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Damjan Jovanovic
Sent: February-14-08 11:19 PM
To: Users Mailing List - Non-Commercial Discussion
Subject: Re: [Callweaver-users] Fax detection while playing a soundfile?

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On Thu, 2008-02-14 at 11:55 -0600, Brandon Mackie wrote:
> Good afternoon,
> 
>  
> 
> Our goal is to have the ability for a voice line to recognize faxes.

Your goal is unattainable. A fax machine only generates the CNG tone in
theory: in practice many use the wrong frequency, wrong cadence, or
don't generate the CNG at all.

If you need to detect faxes with 100% accuracy, either you need a
dedicated fax line, or a "Press 1 to send a fax" IVR where you then
unconditionally call RxFAX() if they press 1.

>  At this point we are using FaxDetect and playing a ringing sound at
> the beginning of the callpath. People with fax-and-walk-away type fax
> machines are just fine. The fax tone is played during the ringing time
> and it gets accepted perfectly. We run into issues with fax-phones or
> generally elderly people. The ideal would be the ability to play while
> the menu is being played. Something along the lines of “Thank-you for
> calling ABC company, if you would like to send a fax you may do so at
> any time, press 1 for our dial by name directory, 2 for sales,etcetc”.
> I tried to figure out the BackgroundDetect application but it didn’t
> appear to do what I was trying to accomplish. Is there something that
> would do this or should I add that to the feature request list?
> 
>  
> 
> -Brandon

Damjan

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