Atm adaptation layer validating the atm header
The format of a minicell is similar to that of an ATM cell, in that each minicell has a header portion and a payload portion.
However, as one skilled in the art will readily appreciate, there are numerous techniques available for improving bandwidth.
More particularly, the present invention relates to the simultaneous and independent transmission of voice and non-voice data over a single, narrowband publically switched telephone network (PSTN) access line.
 Most individuals who access the internet do so through a personal computer located in their home or in their business office.
There are also voice compression techniques, such as those employed in the transmission of cellular voice data that are based on speech analysis. More specifically, there aren't any known telecommunications designs that provide simultaneous transmission of voice and non-voice data, such as internet data, over a single PSTN access line, wherein the voice connection is established between a first set of end-users and the non-voice connection is established between a second set of end-users.
These latter techniques are relatively slow compared with ADPCM. 5,475,691 (Chapman et al.) describes a simultaneous voice and non-voice data modem which is capable of multiplexing and demultiplexing both voice and non-voice data over a single access line for a telephone and a data terminal respectively. It is the ability to both simultaneously and independently transmit voice and non-voice data over a single PSTN line, in a fashion that is invisible to the PSTN, that sets the present invention apart from currently existing telecommunications designs such as those described above.
Moreover, the second sequence of minicells and the first sequence of minicells are transmitted over the PSTN access line simultaneously.