This OID holds an unsigned integer threshold for unavailable seconds (seconds where the signal is completely lost or unusable) during a 15-minute collection interval on ODU Tandem Connection Monitoring B. In network monitoring, any unavailable seconds represent complete service interruption, so even small thresholds are critical—exceeding this value means the link is failing to carry traffic and must be immediately diagnosed. A typical threshold of 0 seconds indicates zero tolerance, but values like 1 second may be used if brief transient dropouts are acceptable.