Abstract: The invention describes a communication appliance (2) having an emergency battery (10) which can be inserted and which is provided with an electronically readable nominal coding; a read device (11) for identifying the nominal coding or a different coding; a signal generating device (11) for producing a new battery identification signal when the nominal coding is identified; and a write device (11, T) which, after the nominal coding has been identified, converts this coding into a different coding.