LAN

Local Area Network - A computer network limited to the immediate area, usually the same building or floor of a building.

LAN Interconnection

Using ISDN an organization can connect LANs at different locations into a WAN (Wide Area Network) on a dial up basis, without the need for a permanent, expensive, leased data link.

LAN Telephony

The convergence of voice and data on a LAN, eliminating the need for separate voice and data networks within an organization.

Latency

The amount of end-to-end delay in a network path or channel.

LCD

Liquid Crystal Display
A display panel found on many phones capable of showing text prompts or messages.

LCR

Least Cost Routing
 - The process that provides customers with cheap telephone calls. Within a telecoms carrier, an LCR team could choose routes from between twenty to over one hundred suppliers for national and internal numbers on a weekly or even daily basis to maintain a competitive cost base and acceptable call quality. The LCR team also has to take route and call quality into account. The quality of route to a destination can vary considerably between suppliers and even from week to week from the same supplier.

LDAP

Lightweight Directory Access Protocol

Leased Line

Lines such as a telephone line or fibre optic cable that is rented for exclusive 24/7 use from your location to another location. The highest speed data connections require a leased line.

LED

Light Emitting Diode - 
A semi-conductor device used as an indicator lamp. Typically these are incorporated into buttons allowing visual indication of calls, voicemail messages and status of other lines and extensions.

Live Call Screening

A facility available on some voicemail systems which allows someone who has diverted his calls to voicemail to listen to a caller leaving a message and pick up the call if he wants to.

Loud Ringing Bell

An audio warning device to alert someone that a call is ringing. It may simply be an extension bell to a telephone or it could be a set of bells around the building so that anyone can pick up the incoming call.