Just an addition to my last post:
I have recorded the call where clearly you can listen the distorted
DTMFs received on GSM PCI card.
Please find the wav file here:
http://www.geocities.com/fichtengolts/asterisk/rec.wav
I'll appreciate if anyone could advise on this matter.
Regards,
Tigran
Tigran Kocharyan wrote:
Hello Matteo,
Thanks for your reply.
I have made an experiment: I put the SIM cards in two mobile phones,
and call each other. Then I send DTMFs from both sides: I can hear the
DTMFS clearly from both sides. This means that the Voice path is clear.
Now I put one of the SIMs in the GSM PCI card. I make a call right
from Asterisk console (OSS/DSP) to the mobile phone. The call connects,
the sound is good, just whenever I press keys on the mobile phone I
hear choppy DTMF tones from the Asterisk side. As a result, the
Asterisk debug console shows the detected DTMFs sometimes dublicated,
sometimes tripled, sometimes normal, and sometimes even not detected at
all. This all happens due to the fact that the DTMFs are received Choppy.
And it is therefore natural that the DTMF detection Algorithm will
sometimes decode a single chopped DTMF tone as seperate digits, or
even ignore the next coming digit, treating it as the chopped tail of
the previous digit.
Just to note, that the opposite direction is working fine; that is
DTMFs sent from the Asterisk reach the mobile phone very clear.
The other interesting moment is that the voice is being heard clear on
both sides, only DTMFs become extorted on the path. (Actually From
Mobile to Asterisk direction only!)
I don't think I need to make ammendments to Asterisk DTMF detection
code and change things there, as far as it works real good for other
channels. I think we need to find out why it happens that DTMS get
choppy and extorted on the way.
Any idea of why this happens?
Thanks.
Regards,
Tigran Kocharyan
Tigran Kocharyan wrote:
This is a forwarded message
From: Matteo Brancaleoni <[EMAIL PROTECTED]>
To: [email protected]
Date: Monday, June 26, 2006, 10:35:38 AM
Subject: [Visdn-hackers] DTMF Detection Problems on VGSM channel
===8<==============Original message text===============
Hi,
On Sun, 2006-06-25 at 00:14 -0400, Tigran Kocharyan wrote:
I guess those GSM cards have problems in DTMF detecting algorithm (I
think DTMF detection burden lies on GSM cards)...
dmtf detection is done with asterisk dsp.
Has anyone faced this issue, or I'm the one to struggle?
never experienced that with many mobiles....
could you try "sniffing" the channel with app_chanspy
is order to hear what the gsm sends out?
matteo.
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