Abstract: A mobile computing and communication device for an emergency occasion is disclosed. The device, for example, is useful for a trapped person under a mound of debris created by a fallen building during an earthquake or a terrorist attack. The invention is based upon a conventional mobile communication device with an additional communication unit. The additional unit is based upon a short-range and ad hoc communication network. The invention is characterized by that a power management unit is used to monitor the remaining power of a battery system for the mobile device. If the power is below a preset threshold value, the main function of the mobile device as a mobile phone is switched off and the reserved power is used to supply energy for the second communication unit, which typically consumes much less power and lasts for very long time.