An overvoltage protector circuit for telecommunication equipments is disclosed. The protector circuit includes a gas discharge tube connected to a communication line for passing any harmful surge currents appearing in the line to ground. A degradation detector circuit is arranged to detect any degradation of the gas discharge tube, the detector circuit comprises a reference gas discharge tube with a higher breakdown voltage than the supervised gas discharge tube and an alarm circuit loop connected to an alarm system. The alarm system is arranged to detect when current is breaking through the reference gas discharge tube and to initiate a degradation alarm.