Fractional atm cells for low bit rate voice

摘要

According to the invention, the system employs standard ATM cells divided into fractional segments or fractions, the header of each standard ATM cell is also the header of the first fraction of a divided cell and each successive fraction of the cell has a header structured as a standard ATM cell header. Always according to the invention, the VPI/VCI value contained in a specified location in the header of the first fraction, identifies the ATM connection multiplexing several low-rate sub-flows as well as the sub-flow to which the first fraction pertains to, while the VPI/VCI values contained in a specified location in the headers of the fractions following said first fraction identify only the respective sub-flows of pertinence. Standard ATM network switches translating the VPI/VCI value of the header of first fraction of the cell to redirect cell and are transparent to the headers of the successive fractions into which the cell is divided; Customizing circuitry in the form of add-on line interface cards installed in a standard ATM switch providing access the headers of all the fractions of the cell and translating the VPI/VCI values relative to respective sub-flow identifiers.