Patent ID: 6480533
Filing Date: 2002-11-12
Classification: H04J,H04L,H04M

Abstract:
A receive modem device configured to receive control signals from a transmit modem device over a fully digital communication channel established therebetween, said receive modem device comprising:a receiver configured to establish a communication session with said transmit modem device and to receive digital data transmitted over said digital communication channel; a control data extractor configured to extract an inband control signal from said digital data, said inband control signal including control data; means for conducting a control procedure during said communication session, said control procedure being responsive to said control data included in said inband control signal, wherein encoded data is transmitted from said transmit modem device to said receive modem device in the form of a plurality of digital codewords during said communication session, said control signal comprises a plurality of control bits; said plurality of control bits are transmitted in a plurality of periodic codewords of said plurality of digital PCM codewords, wherein each of said plurality of digital codewords is formed from a number of bits, and said control bits are transmitted in a consistent bit position associated with said plurality of periodic codewords; wherein said plurality of control bits are retrieved to recover a sequence, and wherein a digital frame slippage is detected by comparing said sequence against a predetermined pattern.