How do I change silent from on to off so phone rings when I get a call?

On the D1680, D1481, and similar phones,
the three levels of ringer loudness plus
"off " are set at the base using the same
[ - ] Volume [ + ] buttons used to adjust
the answering machine message volume.

Pushing the [ + ] and [ - ] keys will
set the ringer to be louder or softer. A
number in the "message counter display"
will report the relative loudness...pushing
[ - ] below level-1 loudness will show
"0" loudness and an announcement of
"Ringer off" will be spoken. From here,
a single push of [ + ] will turn the ringer
on to level-1 and play a ~10 second
sample of the ringer at that volume:
while it is playing the sample ring,
subsequent pushes of [ + ] or [ - ]
will toggle the loudness levels of
( off, 1, 2, 3 ).

Good luck!