Abstract: It is important to report alarm signals rapidly and reliably to the master control units responsible for automatically responding to these alarm signals. Advantageously this is accomplished by transmitting the alarm signals through a switching network of a telecommunications switch, using auxiliary signaling bits provided with each time slot that is switched through the network. The alarm signals are encoded in groups of eight, using one bit of each of eight related time slots to provide an alarm signal within one frame of a digital transmission signal.

Abstract: In large multi-tiered hierarchical alarm systems for high capacity telecommunications transmission systems, it is important to notify the maintenance craft of only the highest alarm, and to notify only when the alarm has been validated by persisting for a sufficiently long time. Advantageously, this is accomplished by timing alarms and freezing the timing when a higher level alarm is detected. If the higher level alarm is no longer present, timing on the lower level frozen alarm signal continues until there is a timeout. A timed out alarm is reported to the maintenance craft.