Ringing signal control circuit for an enhanced subscriber line interface

Abstract

A ringing signal control circuit used in a Subscriber Line Interface Circuit (SLIC) for connecting a ringing signal bus to a subscriber loop. The ringing signal bus transmits ringing signals along the subscriber loop to a subscriber instrument. The SLIC includes a High Voltage Line Interface (HVLI) circuit connected to the subscriber loop and the ringing signal bus is connected to a ringing generator that provides a source of ringing signals. The ringing signal control circuit comprises a logic interface circuit connected via an address/data bus to a central controller that is arranged to receive ringing connection signals from the central controller and to generate a ringing activation signal. A ring timing circuit receives the ringing activation signal and generates a first and second output signals. The second output signal is transmitted from the ring timing circuit at a specific time interval subsequent to the first output signal. A first switching device receives the first output signal from the ring timing circuit and disconnects the HVLI from the subscriber loop. A second switching device receives the second output signal from the ring timing circuit, connecting the ring bus and the ringing signals to the subscriber loop for transmission to the subscriber instrument.