JORGE LUIS CRESPO, DDS
Dentist at Coral Way, Miami, FL

6687369, Feb 3, 2004

Apr 30, 1999

09/302791

Jorge A. Crespo - Miami FL 33165

H04M 100

37937302, 379418

A telephone signal discriminator to be used with one pair of telephone wires and a telephone company with coded ring services. The invention detects the interruptions of the ring signals, shapes them into square waveforms and initially sets off two timer circuits for enabling a shift register or counter for a first predetermined time period. A subsequent second time period is renewed with each set of coded ring signals. The result in the shift register or counter is advance a state in the outputs for each ring. The negated output ending with a low state is presented to the corresponding AND gate, that passes the low state through a corresponding OR gate. The OR gates have one of two inputs commonly connected so that they are disabled during the first period of time. In this manner, only one switch will permit the connection to a telephone outlet connection where one or more telephone devices are connected while the other telephone outlet connections are disabled.