Abstract: In an asynchronous transfer mode switching system, the logical channel number contained in a cell from a user station is translated in an associated one of line circuits to an assigned logical channel number. A self-routing network reads successive bits of the assigned logical channel number of the cell as it propagates through the network to a desired one of cell buffers. A controller receives user information from the line circuits and determines the assigned logical channel number. A waiting buffer is connected from one of the network's outgoing line terminals to one of its incoming line terminals. If the storage level of the cell buffer which is desired by the cell is higher than a predetermined level and if the cell belongs to a class demanding a high grade of service, the controller changes the assigned logical channel number so that the cell is routed from the line circuit through the network to the waiting buffer.