Created by Ryan Harris, last modified by Attila Gulyas on 2020.01.16
Seems to be the DTMF buffer, but only seems to be set on hangup. At least it only shows up in
CHANNEL_HANGUP_COMPLETE , but then all the entered DTMF digits are there.
TODO So where is the buffer, and how to access it and to flush it? (The latter may be important for a long running IVR).
UPDATE: it's not the DTMF buffer...