DTMF signal used as dialing signal in tone telephone applied in many new field widely.

DT MF信号是音频电话中的拨号信号，广泛应用于新一代电话机。

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A kind of hardware and software design of the Amplifying Tone Telephone based on AT89C2051 is introduced in the paper.

介绍了基于AT 89 C 2051单片机的扩音呼叫电话机的硬件与软件设计。

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Like many other developers with a history in telecom, I learned that when you build a telephone switch, regulations say it must provide dial tone in 40ms, a difficult requirement to achieve.

像许多常年混迹于电信行业中的开发人员一样，我所学习到的是，若实现一个电话交换，则一定要在40毫秒内发出拨号音，这是一个难以实现的需求。

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As a side-show, a tone-deaf trade association of struggling European telephone companies known as ETNO put on a full-court press to dupe developing nations into endorsing a plan that would subsidize failing local telcos, many of them state-owned, by taxing the most popular Internet content providers, including YouTube, Facebook, and Yahoo!

FORBES: Requiem for Failed UN Telecom Treaty: No One Mourns the WCIT

It apparently took just one telephone call from the Kremlin to switch the tone from vehemently anti-Western to broadly neutral.

ECONOMIST: Russia's presidency