Abstract: An ATM switch is adapted so that it quickly and efficiently converts a time-sensitive packet received from a source of packets via an incoming trunk into one or more ATM cells. The switch, more particularly, indexes a translation table using the identity of the incoming trunk identity to obtain an assigned AAL2 channel within a virtual channel. The switch then converts the received packet to a particular data unit containing at least the assigned AAL2 channel, determines, as a function of the virtual channel index; a virtual path identifier (VPI) and virtual circuit identifier (VCI); and processes the particular data unit to form the payload for an ATM cell. The switch then forms an ATM cell header containing at least the VPI and VCI, appends the header to each such payload and outputs each cell, in turn, to an output carrying the identified channel.