According to Federal Network Agency jammers are increasingly used by professional thieves to outsmart radio-based security technology.
The answer from viamon on is the GSM monitor. An autonomous system that constantly checks all radio networks and autonomously activates an alarm in case of abnormal faults. It not only raises an alarm light and siren with 116 dB(A), but triggered an alarm via a parallel cable connection for the whole powerplant. In addition, a missing routine signal (heartbeat) can signal a fault.