Three independent dialing buttons (10, 20 and 30) have rhombic
shapes. Independent switching elements (S1)-(S4) are provided on
four corners of the rear surface of each dialing button. Dial numbers (1-9 and
0) and symbols (# and *), grouped four each as (1, 2, 3 and 4), (5, 6, 7 and 8)
and (9, 0, # and *), are marked on the respective four corners of the front surfaces
of the three dialing buttons which are arranged longitudinally on an operation
surface (50). By this construction, the visibility and recognizability of
numbers, etc. can be improved and, further, dialing of numbers can be accurately made.
