Abstract: Apparatus including a telephone instrument for connection to a public telephone system has provision for a call connection to be set up through the system to just a single party upon operation of a single push-button. A plurality of electric switches are preset (usually prior to installation of the instrument) to characterize the directory number of the party that can be called. Upon operation of the push-button, electronic circuitry scans the switches characterizing the directory number to cause the decimal digits of that number to be written sequentially into storage circuitry which subsequently generates a train of impulses in respect of each such digit for transmission to line. There is provision for the scanning operation to be halted for a predetermined period after some of the digits have been written into the storage circuitry.

Abstract: A pushbutton telephone semiconductor dialling circuit power supply comprising a capacitor fed by a diode bridge placed in series with the line looping circuit during dialling. The capacitor size is chosen to charge to at least minimum circuit supply voltage during make periods of line looping, and to keep the circuit supplied during break periods. A constant current charging circuit may be employed to charge the capacitor from the bridge to improve performance, with a diode to power the circuit directly from the bridge while the capacitor is still charging.The microphone-bridging off-normal contacts may be replaced by a transistor switching circuit.