双音多频 DTMF（ Dual Tone Multi-Frequency ）信号，是用两个特定的单

音频率信号的组合来代表数字或功能。在 DTMF 电话机中有 16 个按键，其中

10 个数字键 0 — 9 ， 6 个功能键 * 、 # 、 A 、 B 、 C 、 D 。其中 12

个按键是我们比较熟悉的按键，另外由第 4 列确定的按键作为保留，作为功能

键留为今后他用。 根据 CCITT 建议，国际上采用 697Hz 、 770Hz 、 852Hz 、

94lHz 低频群及 1209Hz 、 1336Hz 、 1477Hz 、 1633Hz 高频群。从低频群和高频群任意各抽出一种频率进行组合，共有 16 种组合，代表 16 种不同的数

字键或功能，每个按键唯一地由一组行频和列频组成-DTMF DTMF (Dual Tone Multi-Frequency) signal, is one of two specific

A combination of audio frequency signals to represent the number or function. In the DTMF telephone has 16 buttons, which

10 number keys 0- 9, 6 function keys*,#, A, B, C, D. 12 of them

Keys is more familiar with the keys, another set from the first four buttons as retention of a functional

Key left for future uses. According to CCITT recommendations, the international use of 697Hz, 770Hz, 852Hz,

94lHz low frequency group and 1209Hz, 1336Hz, 1477Hz, 1633Hz frequency group. From the low group and high-frequency group out of any one frequency for each combination, a total of 16 combinations, the number of representatives of 16 different

Character or function keys, each key uniquely by a group composed of row frequency and column frequency