A mobile radio system comprises first through N-th radio base stations, where N represents a positive integer which is greater than one. On a start-up sequence of an n-th radio base station, a base station control apparatus transmits an n-th individual identifier as a station identifier, to the n-th radio base station to allocate the n-th individual identifier to the n-th radio base station, where n is a variable between one and N, both inclusive. The base station control apparatus transmits a transmission message signal having the n-th individual identifier as a transmission individual identifier to the n-th radio base station to carry out a link connection between the base station control apparatus and the n-th radio base station. In the n-th radio base station, an ATM reception section compares the transmission individual identifier with the n-th station identifier to abandon the transmission message signal when the transmission individual identifier is not coincident with the n-th station identifier. A CPU makes the ATM reception section become a reset state when the ATM reception section continues to abandon the message signal during a predetermined time duration.