Abstract: A scrambling and descrambling system and method for the video and/or audio portions of a broadcast TV signal, for example, broadcast by cable, microwave or communication satellite, includes a telephone modem at the descrambling receiver decoder box which is periodically, for example once per month for a few seconds, connected to a central computer of the head end operator. The decsrambling decoder box is enabled to receive the telephone call by a digital identification code broadcast periodically and associated with each decoder box. Each decoder box has a digital serial number in its Read-Only Memory (ROM) portion of its CPU (central processing unit) and an Electrically Alterable Read-Only Memory (EAROM) containing an alterable look-up table having for each program code a corresponding descrabling code to enable the descrambler.