asterisk users - Jan 2006 - Conversation interrupted by fax

Asterisk SVN-trunk-r7353M (will be moving to 1.2.2 this weekend)
E1 connected to Sangoma A102
SIP phones (Cisco 7960)

I've been making a call from my mobile to the office, when, suddenly the 
conversation is terminated and replaced by a "fax-type" sound. This
has
happened to me several times over the past year, so it's not the version 
of asterisk (we've had cvs trunk and digium TE405 cards running when 
this has happened as well). I've never been able to figure it out.

Today, I was speaking to my wife (I made the call outbound from the 
office to home) and the call went dead. I tried to redial, but kept 
getting the engaged tone. I fired up the * cli, and noticed that there 
was a fax (RXFAX) running on the zap channel that I had previously 
dialled out on. This RXFAX kept running for nearly two minutes, and I 
was unable to call home. However, the second that the rxfax disappeared, 
I was able to call home.

My wife said "it wasn't me, and there was a horrible fax sound on the 
line and I couldn't make any calls".

Now, what is really interesting is the micro second before the call 
dropped, I heard my youngest child start to screech - dinner was being 
served, he was hungry ;)

What I am surmising is that the fax detection is still running on a 
connected call, and decided that the child's screech was a fax machine 
and jumped into receiving a fax .

Is this possible ? I do have fax detection on (zapata.conf). Is there 
anyway of turning fax detection off if the call has been connected ?

Julian.

1	Try disabling faxdetection on your lines, Have youngest go
hungry again to see if that is the problem. (its not child abuse, it's a
small sacrifice for the betterment of the project :-) ). 
2	Assign a DID to child to receive faxes from now and scrap RxFax.

Seriously, High pitches tones and screams have been known to trigger
'false positives' not only for Faxes but for DTMF. I had a friend that
would use a series of words as her password for her Cells VM because
when it asked her for her password when she first set up her VM she
spoke instead of pressing the keys. (She has a Fran Dresher like
voice!!!)


> -----Original Message-----
> From: asterisk-users-bounces@lists.digium.com 
> [mailto:asterisk-users-bounces@lists.digium.com] On Behalf Of 
> Julian Lyndon-Smith
> Sent: Friday, January 20, 2006 1:10 PM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: [Asterisk-Users] Conversation interrupted by fax
> 
> Asterisk SVN-trunk-r7353M (will be moving to 1.2.2 this weekend)
> E1 connected to Sangoma A102
> SIP phones (Cisco 7960)
> 
> I've been making a call from my mobile to the office, when, 
> suddenly the conversation is terminated and replaced by a 
> "fax-type" sound. This has happened to me several times over 
> the past year, so it's not the version of asterisk (we've had 
> cvs trunk and digium TE405 cards running when this has 
> happened as well). I've never been able to figure it out.
> 
> Today, I was speaking to my wife (I made the call outbound 
> from the office to home) and the call went dead. I tried to 
> redial, but kept getting the engaged tone. I fired up the * 
> cli, and noticed that there was a fax (RXFAX) running on the 
> zap channel that I had previously dialled out on. This RXFAX 
> kept running for nearly two minutes, and I was unable to call 
> home. However, the second that the rxfax disappeared, I was 
> able to call home.
> 
> My wife said "it wasn't me, and there was a horrible fax 
> sound on the line and I couldn't make any calls".
> 
> Now, what is really interesting is the micro second before 
> the call dropped, I heard my youngest child start to screech 
> - dinner was being served, he was hungry ;)
> 
> What I am surmising is that the fax detection is still 
> running on a connected call, and decided that the child's 
> screech was a fax machine and jumped into receiving a fax .
> 
> Is this possible ? I do have fax detection on (zapata.conf). 
> Is there anyway of turning fax detection off if the call has 
> been connected ?
> 
> Julian.
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Alexander Lopez wrote:
>1	Try disabling faxdetection on your lines
>
The sad thing is that I believe faxdetect is suppost to automagically 
disable itself after the first several seconds of a call passes.  
However, in my experience faxdetect seems to kick in at any time during 
a call if the audio is just right.

Lee.