DTMF keypad

1209 1336 1477 1633
697
1
ABC
2
DEF
3

A
Row1
770 GHI
4
JKL
5
MNO
6

B
Row2
852 PRS
7
TUV
8
WXY
9

C
Row3
941
*
OPER
0

#

D
Row4
Col1 Col2 Col3 Col4

DTMF = Dual Tone Multiple Frequency