The Loop Maintenance Operations System (LMOS) is a telephone company

trouble ticketing An issue tracking system (also ITS, trouble ticket system, support ticket, request management or incident ticket system) is a computer software package that manages and maintains lists of issues. Issue tracking systems are generally used in coll ...

system to coordinate repairs of

local loop In telephony, the local loop (also referred to as the local tail, subscriber line, or in the aggregate as the last mile) is the physical link or circuit that connects from the demarcation point of the customer premises to the edge of the common ...

s (telephone lines). When a problem is reported by a subscriber dialing the designated number (often (1)+611), 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. The trouble report is then sent to the Front End via the

Datakit Datakit is a virtual circuit switch which was developed by Sandy Fraser at Bell Labs for both local-area and wide-area networks, and in widespread deployment by the Regional Bell Operating Companies (RBOCs). Datakit uses a cell relay protocol simil ...

network, where a Basic Output Report is requested (usually by a lineman). The BOR provides line information including past trouble history and MLT (Mechanized Loop Testing) tests. As LMOS is responsible for trouble reports, analysis, and similar related functions, MLT does the actual testing of customer loops. MLT hardware is located in the Repair Service Bureau. Test trunks connect MLT hardware to the

telephone exchange A telephone exchange, telephone switch, or central office is a telecommunications system used in the public switched telephone network (PSTN) or in large enterprises. It interconnects telephone subscriber lines or virtual circuits of digital syst ...

s or wire centers, which in turn connect with the subscriber loops. The LMOS database is a proprietary file system, designed with 11 access methods (variable index, index, hash tree, fixed partition file, etc.). This is highly tuned for the various pieces of data used by LMOS. LMOS, which was first brought on line as a mainframe application in the 1970s, was one of the first telephone company

operations support system Operations support systems (OSS), operational support systems in British usage, or Operation System (OpS) in NTT, are computer systems used by telecommunications service providers to manage their networks (e.g., telephone networks). They support ...

s to be ported to the

UNIX Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and ot ...

operating system. The first port of LMOS was to

Digital Equipment Corporation Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president unt ...

's PDP 11/70 machines and was completed in 1981. Later versions used

VAX-11/780 The VAX-11 is a discontinued family of 32-bit superminicomputers, running the Virtual Address eXtension (VAX) instruction set architecture (ISA), developed and manufactured by Digital Equipment Corporation (DEC). Development began in 1976. In ad ...

s. Today, LMOS runs on

HP-UX HP-UX (from "Hewlett Packard Unix") is Hewlett Packard Enterprise's proprietary implementation of the Unix operating system, based on Unix System V (initially System III) and first released in 1984. Current versions support HPE Integrity Ser ...

11i systems.

References

See also