Telephone communication system

Abstract

A multi-wire telephone system which facilitates voice and data communication between any two telephones connected to each other with one of a plurality of standard shielded twisted-pair cables. The telephones, which are battery-powered, feature standard telephone operation without a central switching and control station or PBX. Each telephone is provided with a microprocessor which can generate and decode all signals necessary to establish communication with any other telephone in the system. Since a PBX is not required, a break in any phone line will result in two systems operating independently of each other although somewhat degraded performance can be expected, depending upon the nature of the break. Whenever communication is established between two stations in the system, a direct current bias is impressed on the cable interconnecting those stations such that all other stations in the system can determine that that particular cable is in use and can select another cable for communication. Communication is initially established between stations with the use of frequency shift keyed signals sent from one station and retransmitted from the called station before voice communication is established. The telephone system has both private and page communication capabilities and can transmit data in the form of pulsed signals as well as voice signals. The system incorporates a main dispatcher station which can interrupt any private communication in emergency situations and for data transmission.