BRETT DUXBURY gave you an excellent answer...
(Except DTFM is really
DTMF (Dial Tone MULTI-
Frequency (as opposed to MF which the "network"
USED to use to signal
between central offices )))...
GENTLY roll your "
CLARITY" over and look
FIRST for a "PULSE - TONE" slide switch...
Failing to find that the ACTUAL
model number
is going to be YOUR only
FREE advice option.
(unless you can locate your OWN owners manual...
Try your
model number on the internet...
(my favorite site here in the
USA (lookie here)).
ManualsLib Makes it easy to find manuals online
Hope this helps...
Carnac the Magnificent