Intersystem handover

A dual-system mobile station (10) capable of operating in both a first mobile telecommunications system using a first radio access technology (RAT) (12) and in a second mobile telecommunications system using a second RAT (14), comprising:

• a receiver (22) for receiving a pilot signal (18) for providing a strength signal (24) having a magnitude indicative of a strength thereof;
• and
• a pilot signal evaluator (26), responsive to said strength signal (24) from said receiver (22) for evaluating said strength signal for determining whether to carry out an inter-system handover from operating said mobile station in said second mobile telecommunications system using said second RAT to operating said mobile station in said first telecommunications system using said first RAT and for providing a signal (34) indicative thereof.

A base station (11) of a second generation (GSM) mobile telecommunication system having an antenna for radiating signals to mobile stations in a cell thereof, characterized by a pilot signal transmitter (20) for transmitting a pilot signal (18) having a carrier frequency identical to that of a carrier of a radio access technology (14) of a third generation mobile telecommunication system, said pilot signal for conveying information relating to its identity and configuration parameters needed by a dual-system mobile station capable of operating in both said second and third mobile telecommunications systems for use in making a handover decision to change from operating in said third generation mobile telecommunication system to operating in said second generation mobile telecommunications system.