MEJORAS EN SISTEMAS DE LLAMADAS SELECTIVAS CODIFICADAS.

摘要

A telephone party line signalling system which employs an electronic monitor circuit at the output end of a central office switching circuit to detect the code of any coded ringing signal emanating from the office. Responsive to this code, the monitor circuit stores and re-encodes these signals into a signal in other forms. The re-encoded signal is sent out over a called line, the other signal form being a multifrequency set of tones which characterize a particular digit in the well known pushbutton tone signalling, for example. Each subscriber station is adapted to respond to the combination of the frequencies comprising these tones and to locally supply ringing current to its own subscriber station.