Abstract: A geographically distributed multiprocessor system is implemented by locating groups of processors at nodes which are interconnected by way of a transport network and which are connected by way of local lines to customer terminals and hosts. Each processor supports a plurality of processes which communicate with other processes in the same processor by way of internal links and with other processes in other processors by way of combinations of internal links and external communication links. Interface processes exchange data between the internal and external links. A process can initiate a call to any other process and define the communication parameters for exchanging data information by selecting the appropriate internal link and supplying the code defining the communication parameters to the selected internal link.