Patent ID: 7340059

Claim:
An apparatus comprising: an interface to be coupled to an item of telephony equipment; and a scrambler coupled to the interface to provide an output signal to the interface, the scrambler including: a logic circuit having a plurality of inputs and an output, one of said inputs for receiving an input signal to be scrambled by said scrambler, said input signal including a sequence of input bits, said output for supplying said output signal to said interface, said output signal including output bits; a shift register coupled to the output of the logic circuit and having a plurality of taps, said shift register for storing ones of said output bits; a plurality of gates each having a respective input coupled to one of the taps and a respective output coupled to a respective one of the inputs of the logic circuit; and a mask register coupled to the plurality of gates and capable of storing a plurality of bits, each bit stored in the mask register to control a respective one of the gates.