C400 (ZMM) - How To Change The Volume
You will need the ADMIN Card to log into the menus
Press the M/OK button (a padlock will display) swipe the Admin card
Using the arrows go to "PERSONALIZE" and press M/OK
Using the arrows go to "VOICE" and press M/OK
Using the arrows go to "VOLUME" and press M/OK
In this screen you can increase (or decrease the volume) using the left or right arrow.
When the volume is set, press "CONFIRM (OK)" and the ESC several times to exit the menus.