Tyco Electronics MM102014V1 - Manual (Page 44)

MM102014V1, Rev. G
5.18 DUAL-TONE MULTI-FREQUENCY KEYPAD
Dual-Tone Multi-Frequency (DTMF) is the system used by touch-tone telephones. DTMF assigns a
specific tone frequency to each key so a microprocessor can easily identify its activation. The radio
supports DTMF using a microphone with an alphanumeric keypad (see Figure 5-6). This allows for
specific tasks such as entering a user ID and password, or selective calling.
When a key on the DTMF keypad is pressed, a single low-pitched tone will be heard from the
microphone. The key tones are not adjustable.
Although the “Q” is not shown on the 7 key and the “Z” is not shown on the 9 key of the
DTMF keypad, both letters are supported by the system. To enter a “Q” from the keypad,
press the 7 key 3 times (7, P, Q). To enter a “Z” from the keypad, press the 9 key 5 times.
Because the Q and Z are recognized by the system, the number of presses required to
enter other characters from those keys may be different. For instance, 5 key presses are
required to enter an “S” using the 7 key (7, P, Q, R, S).
If the key is pressed too many times, continue pressing the key to scroll through the
remaining characters and returning to the first character. Remember to consider the
characters not shown on the keys.
Figure 5-6: DTMF Microphone Keypad
44