[asterisk-users] Sipgate > DTMF not detected

[listuser at spamomania.co.uk]

I raised an issue with Sipgate because my Asterisk 1.6 plain refuses to
recognize digits pressed on a keypad coming in from a Sipgate trunk.

There answer was to set this:
dtmfmode=rfc2833

in the general section of sip.conf

This has made no difference. I've tried a range of settings (auto,
rfc2833,info) but no matter what, it plain refuses to pick up key
presses.

Locally, if I call from an extension on an ata or a softphone, it works
flawlessly (I have no fxo, everything is SIP based).

It's extremely frustrating and I would be grateful if anyone could offer
some help troubleshooting and fixing this?