According to the inventive method, a message is transmitted from an operating mobile radio network (NW2) to a terminal (MS1a) that identifies coding techniques (UEA-NW) supported by the operating mobile radio network in order to establish a connection between the terminal (MS1a) that supports a number (UEA-MS) of coding techniques and the operating mobile radio network (NW2). The terminal selects, if available, a coding technique (UEA) that is supported by the terminal and the operating mobile radio network (NW2), and the connection is operated using the coding technique selected by the terminal. If no coding technique is available that is supported by the terminal and the operating mobile radio network, the connection is operated uncoded only upon prior authorization.