Communication control system using an asynchronous transfer mode network

A communication control system using an ATM network and constructed by a small number of virtual connections. Fixed or semi-fixed virtual connection connect each user interface and a corresponding connectionless service processor and interconnect the connectionless service processors. A data packet received from a user terminal is converted into an ATM cell by the user interface and delivered to the connectionless service processor through the virtual connection. In the connectionless service processor, an ATM cell is transferred into a virtual connection located in the direction in which the destination user interface is provided to thereby carry out routine to the ATM cell.