Hello goose, I am not sure if you are still experiencing a problem with this. You might want to make sure you have the “dtmf-relay” command under the appropriate dial peer that is pointing to your PBX. As a simple test, if you have FXS ports on your Cisco gateway, hook up a regular analog phone to it, run debugs or other tests to check if DTMF is being passed. If yes, then the problem is on your PBX side. If not, then focus on the Cisco gateway and try a different IOS version.