The invention relates to a method and devices for mutual communication between devices, and to computer programs enabling such communication. According to the invention, in a first device is controlled a transmitter module operable in a local radio communications network to transmit a sequence of radio signal pulses representing a predetermined code. In at least one second device a receiver module is scanning said local radio communications network to detect said predetermined code. A contact network of the user of said at least second device is accessed, and the predetermined code is checked in the second device against the user's contact network for a match stored in the network profiles for the contacts. Then a validation key is fetched, that relates to a matching contact found in said contact network, and a connection establishment request containing the validation key is sent over said local radio communications network from the second device to the first device. Thus the origin of the connection establishment request is validated in the first device.