A BUG IS A DEVICE FOR LISTENING TO CONVERSATIONS IN A ROOM. A TAP IS FOR LISTENING TO TELEPHONE CONVERSATIONS. A TELEPHONE BUG IS A BUG ATTACHED TO TELEPHONE LINES. IT WILL PICK UP CONVERSATIONS IN THE ROOM EVEN WHEN THE TELEPHONE IS HUNG UP. (SUCH BUGS USUALLY SERVE AS TAPS AS WELL.) BRIEF EXPLANATIONS ARE PRESENTED OF THE TECHNICAL ASPECTS OF VARIOUS TELEPHONE TAPS AND BUGS. PARTICULAR ATTENTION IS DIRECTED TO EACH DEVICE'S LEVEL OF SOPHISTICATION, EASE OF INSTALLATION, AND SUSCEPTIBILITY TO DETECTION. ONE BUG, CALLED AN INFINITY TRANSMITTER, ENABLES THE EAVESDROPPER TO LISTEN IN ON CONVERSATIONS IN A ROOM BY CALLING THE SUBJECT, APOLOGIZING FOR A WRONG NUMBER, AND THEN NOT HANGING UP WHEN THE SUBJECT HANGS UP. THE EAVESDROPPER ACTIVATES A 'HOOKSWITCH BYPASS,' WHICH MAKES THE TELEPHONE ACT AS IF IT WERE OFF THE HOOK AGAIN (I.E., TURNS IT INTO A BUG). IN THE UNITED STATES, THE EAVESDROPPER CAN ACCOMPLISH THIS WITHOUT MAKING THE SUBJECT'S TELEPHONE RING. UNLIKE OTHER HOOKSWITCH BYPASSES, THE INFINITY TRANSMITTER DOES NOT REQUIRE A LISTENING POST CONNECTED BETWEEN THE TELEPHONE AND THE EXCHANGE, MEANING THAT THE EAVESDROPPER CAN LISTEN FROM A CONTINENT AWAY. THE REVIEW ALSO DESCRIBES AND ASSESSES THE LATEST DEVICES FOR DETECTING TAPS AND BUGS, AS WELL AS A DEVICE THAT PREVENTS CERTAIN TYPES OF TAPS KNOWN AS THE WIRETAP TRAP, THIS DEVICE RESEMBLES THE 'BLACK BOX' THAT PERMITS PEOPLE TO MAKE CALLS TO A TELEPHONE WITHOUT BEING CHARGED. A SIDEBAR TO THE ARTICLE SURVEYS THE LEGALITY OF OFFICIAL AND PRIVATE TAPPING IN GREAT BRITAIN, NOTING THE WIDE RANGE OF CIRCUMSTANCES IN WHICH SUCH ACTIVITY IS LEGAL. (LKM)