A radio controller monitors a radio channel for a first period of time and determines a first indication of signals received without detecting synchronization or with detecting synchronization but failing error correction during that time. Responsive to determining that the first indication is above a predetermined threshold indicative of an interference condition, causing an instruction to be broadcast identifying a subset of subscriber devices allowed transmitting random access requests on the radio channel. The radio controller monitors the radio channel for a second period of time and determines a second indication during that time. If the second indication is an improvement over the first indication, the radio controller determines that the interference condition is caused by the mass random access event.