[Asterisk-Users] DTMF tones from PSTN not reaching SIP device

[Bruce Komito]

Greetings, I am PRIs connected to a Cisco 36xx gateway, which in turn
connects to Asterisk via SIP.  The problem I am having is that DTMF tones
originated on the PSTN side are not heard on the SIP device.  On the other
hand, tones originating on the PSTN side are received by Asterisk when
talking to voicemail or an autoattendant.

>From the Cisco debug, I can see the Cisco sending NTE (RFC2833) RTP
packets to Asterisk and it appears that Asterisk is propogating them down
to the SIP device.  However when tones are pressed on the PSTN side, all
that can be heard on the IP phone is silence.  I've tried this on three
different IP phones (Cisco 79xx, ZIP2 and Sipura) and they all behave the
same, leading me to conclude it isn't a phone config problem.  Everything
(Cisco and phones) are configured for dtmfmode=rfc2833.

Anyone got any ideas?

TIA

Bruce Komito
High Sierra Networks, Inc.
www.servers-r-us.com
(775) 236-5815