Abstract: The objective of the invention is a system, comprising an ISDN-network, having access through the intelligent network service switching point (SSP) to the services offered by the intelligent network service control point (SCP), a data network, in which at least one computer has a data network-address, and a gateway connecting the networks. The call can be connected to a telephone integrated to the computer, so that the data network-address used by the subscriber's computer and the subscriber's personal identifier are at first transferred to the gateway, which codes the data network-address. Thereafter the coded address, the gateway address and the subscriber's personal identifier are transmitted to the intelligent network and recorded in the database of the Service Data Point (SDP). The intelligent network has now the required data to create the speech connection between the mentioned subscriber and another subscriber.