Transmitting an emergency message in direct mode if trunked mode is not feasible

摘要

A mobile communication unit 101 for a cellular communication system 100 comprises direct mode communication means 127, 129 for communicating in a direct mode to other communication units 109 of the cellular communication system 100 and trunked mode communication means 125, 129 for communicating in a trunked mode to a serving base station 103. A user interface 119 may receive an emergency input and in response a feasibility processor 123 determines a feasibility of communicating in the trunked mode. An emergency controller 121 selects between communicating an emergency message in the direct mode and in the trunked mode in response to the feasibility. Specifically, the emergency message may be transmitted in trunked mode if this is feasible and will otherwise automatically be transmitted in direct mode. The invention is applicable to a TETRA cellular communication system.