A computer communications network comprises a plurality of interconnected ATM switches forming a WAN or LAN area network over which ATM cells are transmitted, and a plurality of user devices including LAN interface adapters for connection to one or more to local area networks (LANs). An interface device connects at least some of the respective ATM switches to the LAN interface adapters. The interface adapts the ATM cells for transport over the LANS. The user devices can thus communicate through the LAN interface adapters transparently with the wide area network.