A mobile telecommunications system, including: a first base station configured to operate in a first mobile telecommunications system, a second base station configured to operate in a second mobile telecommunications system, a third base station configured to operate in the first mobile telecommunications system, and a user equipment configured to operate in the first mobile telecommunications system and in the second mobile telecommunications system; wherein: the user equipment is configured to measure a property of a first received reference signal from the first base station; the user equipment is configured to measure a property of a second received reference signal from the second base station, or the second base station is configured to measure a property of a second received reference signal from the user equipment; the user equipment is configured to switch from the first base station to the second base station as a serving base station based on the property of the first received reference signal and on the property of the second received reference signal; the user equipment is configured to switch from a first radio resource control function specified in the first mobile telecommunications system to a second radio resource control function specified in the second mobile telecommunications system; the second radio resource control function is configured to establish a connection to the second base station; the system being characterized by: the user equipment is configured to measure a property of a third received reference signal from the third base station; the second radio resource control function is configured to establish a connection to the third base station in addition to the connection to the second base station; and the second radio resource control function is configured to release the connection to the third base station in accordance with expiration of a timer, wherein duration of the timer may be predetermined by the second or third base station (6, 8). a first base station configured to operate in a first mobile telecommunications system, a second base station configured to operate in a second mobile telecommunications system, a third base station configured to operate in the first mobile telecommunications system, and a user equipment configured to operate in the first mobile telecommunications system and in the second mobile telecommunications system; the user equipment is configured to measure a property of a first received reference signal from the first base station; the user equipment is configured to measure a property of a second received reference signal from the second base station, or the second base station is configured to measure a property of a second received reference signal from the user equipment; the user equipment is configured to switch from the first base station to the second base station as a serving base station based on the property of the first received reference signal and on the property of the second received reference signal; the user equipment is configured to switch from a first radio resource control function specified in the first mobile telecommunications system to a second radio resource control function specified in the second mobile telecommunications system; the second radio resource control function is configured to establish a connection to the second base station; the system being characterized by: the user equipment is configured to measure a property of a third received reference signal from the third base station; the second radio resource control function is configured to establish a connection to the third base station in addition to the connection to the second base station; and the second radio resource control function is configured to release the connection to the third base station in accordance with expiration of a timer, wherein duration of the timer may be predetermined by the second or third base station (6, 8). the user equipment is configured to measure a property of a third received reference signal from the third base station; the second radio resource control function is configured to establish a connection to the third base station in addition to the connection to the second base station; and the second radio resource control function is configured to release the connection to the third base station in accordance with expiration of a timer, wherein duration of the timer may be predetermined by the second or third base station (6, 8).