[Asterisk-Users] dtmf tone clamping in calls to external ivr

[Mark Mickan]

Hello,

I'm having trouble working out how to send DTMF tones to an external
IVR.  My system has an analog phone connected to a TDM400P card, a SIP
software phone (Zultys LIPZ4) and is connected to a BRI in Australia
with a NETjet-S card.  I'm using ISDN4Linux and a 2.4.25 kernel patched
with the ISDN audio patch from Traverse (which allows the card to do
voice).

DTMF works fine between the analog phone and the SIP phone - I can hear
the tones on the SIP phone when I use dtmfmode=inband and I can see them
with dtmfmode=info, and I hear them on the analog phone.

When I bring the ISDN link into the picture, such as to call to my phone
banking, it doesn't recognise any tones.  I have also tested this by
dialling my mobile (via the ISDN link) and it sounds like Asterisk is
clamping the tones - I hear the very first part of the tone then the
call is muted for the remaining duration of the tone.  I _can_ hear the
tones on my analog phone when I press them on the mobile, however, so it
seems the problem is only in the one direction.

I've been grepping the mailing list archives and found Pauline
Middelink's isdn-dsp patch (which I've applied in an attempt to solve
this problem - I've now got "features=dtmf,noquelch" in my modem.conf),
but that seems to relate to digits coming _from_ the ISDN _to_ Asterisk,
not the other way around.  Looks like some people have run into my
problem before, but I cannot find any conclusions in the list archives.

Can anyone help?

Thanks in advance,
Mark

-- 
Mark Mickan <mark.mickan at articul-8.com>