Adaptive telephone handset interface

Abstract

An adaptive handset interface for interfacing a two-wire analog telephone instrument to a telephone set having a base unit connected to a handset via a four-wire handset cable. The interface is suitable for use with a variety of telephone sets produced by different manufacturers despite differences in the signalling between the telephone base and the handset. This is because, upon initiation of a learning technique, the interface automatically adapts to variations in signalling between the telephone base and handset among the different telephone manufacturers. To use the interface, the handset is unplugged from the handset jack of the telephone base and plugged into a handset jack of the interface. In addition, a four-wire cable is plugged into a telephone base jack of the interface and into the handset jack of telephone base. The interface includes a modular jack for coupling the interface device to the two-wire telephone instrument. The interface device incorporates three different techniques for learning the signalling characteristics of the telephone set: a self-contained technique which is executed under control of a control circuit contained within the interface; a technique which requires the user to dial a telephone number to couple the interface to an automated host system which then controls the learning process; and a technique which requires the user to dial a telephone number and, then, a technician controls the learning process. The latter two of the three techniques are used only if the self-contained technique is not completely successful.