Help DTMF being repeated randomly

Hello Guru’s

Not sure what has happened, but use webex for a lot of my conference calls, and it uses DTMF to identify conference. I have a collection of Cisco 7970’s, 7971 and adore soft phone, the fault is across all of these.
using the raspberry Pi as freepbx server.

DTMF numbers are randomly being repeated.

Troubleshooting so far:
tried changing the DTMF in the SIP file:

tried altering the DTMF mode in freepbx.
auto/rfc2833, the SIP ones don’t seem to work

tried an older version of freepbx, different phones, etc.

is there a way to debug what is being sent, or option to add a dtmf delay, or another fix?

many thanks, Adrian.

looks like a voipdiscount issue, as have configured sipgate as outgoing trunk/route and works fine, so have altered my dial plan to use sipgate for my conference calls until I hear back from voipdiscount