Method and apparatus for providing privacy/security in a communication

Abstract

Apparatus and methods are disclosed for providing privacy on communications systems which include radio links, such as cellular telephone, marine radiotelephone, IMTS, and RDSS systems, in a manner which does not require a scrambler/descrambler at each called party location. The apparatus includes a base module having a call diverter connected to the public switched telephone network through two standard telephone lines. A bypass interface circuit is connected to the call diverter between the connections to the two telephone lines to selectively connect a scrambler/descrambler in series with the two telephone lines. In operation, a mobile telephone, such as a cellular telephone, places a call to the telephone number of the first telephone line to cause the call diverter to place the second line off-hook and supply a dial tone from the second line through the call diverter and the first line back to the cellular telephone. The cellular telephone then dials the number of the desired called party to establish a communications path. The cellular telephone causes the call diverter to connect the scrambler/descrambler in series with the communications path and activates a scrambler/descrambler at the cellular telephone location to provide privacy against unauthorized monitoring of the radio link, without requiring a scrambler/descrambler unit at the called party location.