An arrangement and method for establishing and maintaining a connection between users' communication devices via a public data network. Communication devices belonging to users of a system are terminals of a telecommunication network, say mobile phones, and, in addition, they are adapted to a link to a data network via a wireless transfer system. Interfaced with the data network there is at least one server that keeps a register of communication devices. A communication device brought near a data network terminal reports itself to the server using a device-specific identifier. This reporting message also contains network address of the terminal. When a connect request arrives from a communication device via a terminal, the server provides for necessary network connection if the called device specified in the connect request can be reached.