A mobile telephone operated from a vehicle battery comprises an input line for providing a signal indicative of the ignition stage of the vehicle. The telephone has a menu facility for selecting an automatic answer mode. The telephone goes off-hook automatically after a predetermined interval if the automatic answer mode has been selected and the signal on input line (11) indicates that the ignition is turned on. An incoming call can thus be answered without the user having to physically touch the telephone. On the other hand the automatic answer mode is not enabled when the ignition is off, i.e when the telephone is more likely to be unattended.