Command and control signalling method and apparatus

摘要

A local communication apparatus (e.g., a modem) is arranged to detect when a remote communication apparatus desires to switch from the data mode and enter a command/control mode. To accomplish mode switching, the remote apparatus sends a scrambled escape pattern, scrambled using a proprietary polynomial, over the data channel. After detecting the escape pattern the local apparatus switches to the command/control mode. In this mode, the remote and local apparatuses communicate using the proprietary scrambler/descrambler polynomial.