| 摘要 |
<p>In areas utilizing telephone switching equipment that will only accept dial pulses, a conversion unit, that fits into the space formerly occupied by the dialing mechanism in a standard telephone subscriber's unit, provides touch-pad dialing. The conversion unit accepts input signals, representing digits, from a standard 3 x 4 matrix touch-pad at an asynchronous rate and starts out-pulsing at the required pulse repetition rate as soon as the first digit signal is received. During each touch-pad button depression, an audio tone is supplied to the subscriber unit earpiece. The conversion unit provides for programmable toll restriction that permits selective prohibition of outpulsing at each subscriber unit. At the instant a restricted input signal is received, the conversion unit provides a steady audio tone to the earpiece and stops out-pulsing. To prevent hookswitch dialing, the conversion unit extends the break period of the electronic pulsing switch. The entire conversion unit is powered by the DC voltage on the C.O. line with negligible transmission attenuation.</p> |
