Abstract: A signal intercept system intercepts an international calling frame, modifies a specific set of bits and then retransmits the frame in real time. The signal intercept system includes a communications processor and a signalling link interface. In one arrangement, the signalling link interface includes two intercept and transmit connectors and a coprocessor connector. In one arrangement, the communications processor includes a computer and a communications coprocessor. The computer maintains a data base with tables of such data as invalid calling card numbers. A computer program initializes and starts the communications coprocessor which handles high speed signal capture, manipulation and high speed signal retransmission. The communications coprocessor also interacts with the computer's data base to alter table parameters.