| 摘要 |
Dial tone detection circuitry is employed in a telephone of the type which has its dialing mechanism incorporated into the handset. The dial tone detection circuitry is connected to an annunciating means which indicates to a user that dial tone is present without the need to bring the handset to the user's ear. The dial tone detection circuitry my also be connected to the telephone's automatic redial circuitry to ensure efficient operation of the redial function.
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