| 摘要 |
A hold circuit arrangement for a telephone, wherein the telephone is coupled to an extension release circuit of an external telephone, the hold circuit comprising an input control terminal; a tri-state input device used for generating a signal for the input control terminal; a power supply used for providing a high impedance level for the input control terminal; a hold button circuit used for allowing a hold button of the telephone to convert a status of the hold circuit through the tri-state input device after the hold function is activated regardless of whether the telephone is off-hook or on-hook; and a detecting circuit used for alternately providing a high impedance high level signal or a high impedance low level signal to detect the status of the tri-state input device when the hold function of the telephone is activated, and deciding whether the telephone is hold or not, and signaling the power supply to stop providing the high impedance level signal to the input control terminal when the hold function of the telephone is activated.
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