| 摘要 |
PURPOSE: A DTMF(Dual Tone Multi Frequency)/ring-back tone sending device of a PBX(Private Branch eXchange) is provided to use a transmission highway for subscribers of an exchange by installing a DTMF/ring-back tone generator in a switch circuit unit. CONSTITUTION: A controller interface(400) generates a control signal and transmits it to a switch circuit unit(420). A clock interface(410) transmits a clock 2M, a clock 32M and a header of a PCM signal to the switch circuit unit(420). The switch circuit unit(420) generates a tone data for sending a call number received from a caller to an office line connector(440). The switch circuit unit(420) searches a corresponding PCM address of an office line circuit unit from the tone data and stores it in a buffer unit of a corresponding office line. The switch circuit unit(420) synchronizes the tone data with clock information received from the clock interface(410) and sends it to a reception highway.
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