技术在快速发展进步。因此，我们建立了易于使用的术语汇编，帮助您更好地了解影响您业务的术语、技术和趋势。
Used for telecommunication signaling over analog telephone lines in the voice-frequency band between telephone handsets and other communications devices and the switching center. The version of DTMF that is used in push-button telephones for tone dialing is known as Touch-Tone. DTMF is standardized by ITU-T Recommendation Q.23. Other multifrequency systems are used for internal signaling within the telephone network.
