[Freeswitch-users] Strange DTMF Tones On Inbound Calls

Michael Collins msc at freeswitch.org
Tue Apr 3 19:30:32 MSD 2012

On Tue, Apr 3, 2012 at 8:17 AM, Daniel Knaggs <
Daniel.Knaggs at realitysolutions.co.uk> wrote:

>   Update, it would appear (so far) that this has worked.****
> ** **
> I can see in the log numerous “Rogue digit: DTMF 'A' received” entries
> (and also for “C”) and I’ve asked the users if they have heard any more
> tones and they haven’t.****
> ** **
> ** **
> Thanks, Michael.   So we’ve managed to work around it, but how can I track
> down what is generating these tones to begin with?  Is my earlier spectrum
> analysis of a call any good?

I don't think we ever truly answered the question of whether or not these
rogue digits are phantoms. Remind me: how did you capture the audio on
which you did the spectrum analysis? I recommend using ftdm dump, which is
nice because it captures raw audio in either direction, and if I understand
correctly it is what's "on the line" - if those rogue digits are coming
from the other end they'll show up in the raw dump. If those digits are not
in the raw audio then most likely you're looking at a false positive from
the DTMF detector, in which case you've got a bit of a conundrum because
you've got hardware from Digium and software from Sangoma and you need to
figure out where to begin looking...

BTW, feel free to keep the BDA's in there and just add your transfer digits
to the digit action realm and you can avoid using bind meta app. BDA is the
preferred method nowadays.

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