a) DTMF C+D (up/down key) do work only after another key was used before.
Example PTT+'D1#' does not send the D but changes the zone and stops TX.
Workaround for Echolink: Use '*D1#'
b) Setting the radio channel type to 'A+D' (analog and digital reception with analog TX) no DTMF is sent.
Two issues here on a AT-D878UV, Firmware 1.17:
a) DTMF C+D (up/down key) do work only after another key was used before. Example PTT+'D1#' does not send the D but changes the zone and stops TX. Workaround for Echolink: Use '*D1#' b) Setting the radio channel type to 'A+D' (analog and digital reception with analog TX) no DTMF is sent.