[Asterisk-Users] Need help with DTMF issues and IVR systems

[Paul Cheng]

Hi,

With Asterisk and SIP phones (Cisco ATA186, Grandstream BT102), I'm 
having an issue with DTMF passing correctly to IVR systems like 
customer support phone numbers, voicemail, etc.:

1) If I set DTMF to SIP INFO, DTMF works for ISDN4LINUX calls to IVR 
systems with the CiscoATA186, but not with the Grandstream (this could 
be a bug) -- BUT the Asterisk Voicemail doesn't detect the DTMFs. SIP 
calls to gateways and other SIP phones work fine.
2) If I set DTMF to INBAND, there are problems with double-detection 
and it doesn't work with LBR codecs. However, in this mode, calls to 
IVR systems via I4L work with the Grandstream.
3) If I set DTMF to rfc2833, voicemail works, but ISDN4LINUX calls 
don't pass the DTMF to IVR systems from either the Cisco or the 
Grandstream.

Has anyone had any luck getting one setting to work across all 
channels? The problem is not in the initial call, but usually after the 
call is connected, the DTMF doesn't get passed.

What baffles me is why SIP INFO doesn't work with Asterisk AppVoicemail.

Any hints, suggestions, experiences would be greately appreciated.