Apparatus and method for remotely determining the presence of un
Apparatus to prevent unauthorized use of telephone lines
Communication terminal having functions of detecting and prevent
Line sharing multipoint POTS splitter masking noise
Lockout device for preventing telephone eavesdropping from an ex
Method and apparatus for prohibiting unauthorized use of a telec
Multifunction adaptive telephone line measurement method and sys
Radio telecommunication network and method for unobtrusive call
Telephone privacy circuit
Wire tap detection device with passive testing
Wiretap detector and telephone loop monitor