Loop maintenance operations system
The Loop Maintenance Operations System (LMOS) is a telephone company trouble ticketing system to coordinate repairs of local loops (telephone lines). When a problem is reported by a subscriber, it is filed and relayed through the Cross Front End, which is a link from the CRSAB (Centralized Repair Service Answering Bureau) to the LMOS network.
Source: Wikipedia — Loop maintenance operations system (CC BY-SA 4.0)