This read-only INTEGER reports the specific type of alarm on the trunk, one of resources-unavailable(1), communication-failure(2), unknown(3), failed(4), or looped(5), and only has meaning when parTrkAlarmStatus indicates an alarm is present. An administrator uses this to distinguish the root cause, for instance whether the platform simply lacks the resources to make the interface a trunk versus message exchange with the neighboring node having failed. For example, seeing commfail(2) tells the operator the neighboring nodes have lost message exchange over this trunk, pointing toward a link or connectivity problem rather than a local resource shortage.