Telecom Dictionary

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LAN (IEEE 802.3 10BaseT)
LAN (Local Area Network) is an Institute of Electrical and Electronic Engineers specification for a 
class of LANs using four-pair unshielded twisted pair (UTP) cable. See Local Area Network.

LAN 
local area network

LATA 
local access and transport area

LCR 
least-cost routing

LDN
listed directory number; generally an organization's main telephone number that appears in the 
telephone book.

LDN 
listed directory number

LEC 
local exchange carrier

Line
See loop transmission facilities.

Local Access And Transport Area (LATA)
LATA is a geographic area (called an "exchange" or "exchange area" in the MFJ) within each 
BOC's franchised area that has been established by a BOC in accordance with the provisions of 
the MFJ for the purpose of defining the territory within which a BOC may offer its telecommunications services. In 1989, there were 198 LATAs, also referred to as market service 
areas (MSAs), in the United States.

Local Area Network (LAN)
LAN is a premises high-speed (typically in the range of 10 Mbps) data communications system 
wherein all segments of the transmission medium (typically coaxial cable, twisted pair or optical 
fiber) are contained within an office or campus environment.

Local Channel
In LEC tariffs, a local channel is the local loop that connects customer premises to serving LEC 
wire centers. In IXC tariffs, the network components (transmission, switching, other) used to 
connect customer premises to serving IXC POPs.

Loop Length
Typically, loop length is a complete electrical circuit; the pair of wires that winds its way from the 
central office to the telephone set or system at the customer's premises.

Loop Signaling
Loop signaling is a method of signaling over dc circuit paths that utilizes the metallic loop formed 
by the line or trunk conductors and terminating circuits.

Loop Start
Loop start is a supervisory signal given at a telephone or PBX in response to closing the loop's DC 
current path.

Loop Transmission Facilities
Loop transmission facilities connect switching systems to customer premises equipment 
throughout the serving area. A loop is a transmission path between a customer's premises and a 
LEC central office. The most common form of loop, a pair of wires, is also called a line. A loop" 
can be derived from digital loop carrier (DLC) systems also referred to as subscriber loop carrier 
(SLC) systems.

LSI 
large-scale integrated circuit