In
telecommunication
Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that fe ...
, a private line is typically a telephone company service that uses a dedicated, usually unswitched point-to-point circuit, but it may involve private
switching arrangements, or predefined
transmission
Transmission may refer to:
Medicine, science and technology
* Power transmission
** Electric power transmission
** Propulsion transmission, technology allowing controlled application of power
*** Automatic transmission
*** Manual transmission
*** ...
physical or virtual paths. Most private lines connect only two locations, but some have multiple drop points. If the circuit is used for interconnecting switching systems, including manual switchboards, it is often called a
tie line.
Among subscribers to the
public switched telephone network
The public switched telephone network (PSTN) provides Communications infrastructure, infrastructure and services for public Telecommunications, telecommunication. The PSTN is the aggregate of the world's circuit-switched telephone networks that ...
, the term ''private line'' is often erroneously used to describe an ''individual''
telephone line
A telephone line or telephone circuit (or just line or circuit industrywide) is a single-user circuit on a telephone communication system. It is designed to reproduce speech of a quality that is understandable. It is the physical wire or ot ...
for service for only one subscriber, as opposed to a
party line with multiple stations connected.
In radio or
wireless telephony
Wireless communication (or just wireless, when the context allows) is the transfer of information between two or more points without the use of an electrical conductor, optical fiber or other continuous guided medium for the transfer. The most ...
, ''Private Line'' is a term trademarked by Motorola to describe an implementation of a
Continuous Tone-Coded Squelch System
In telecommunications, Continuous Tone-Coded Squelch System or CTCSS is one type of in-band signaling that is used to reduce the annoyance of listening to other users on a shared two-way radio communication channel. (See squelch.) It is sometimes ...
(CTCSS), a method of using low-frequency subaudible tones to share a single radio channel among multiple users. Each user group would use a different low frequency tone. Motorola's trade name, especially the abbreviation ''PL'', has become a
genericized trademark
A generic trademark, also known as a genericized trademark or proprietary eponym, is a trademark or brand name that, because of its popularity or significance, has become the generic term for, or synonymous with, a general class of products or ...
for the method. General Electric used the term ''Channel Guard'' to describe the same system and other manufacturers used other terms.
A later digital version of a private line is called ''digital private line'' (DPL).
Advantages of private lines are:
* High security as one dedicated link is provided
* Always available
* Instant data transmission
Types
* PLNA - Private Line No Apparatus
* PLNE - Private Line No Equipment
* PLAR - Private Line Automatic Ringdown (think the "Red Phone")
See also
*
Leased line
*
Dedicated line
In computer networks and telecommunications, a dedicated line is a communications cable or other facility dedicated to a specific application, in contrast with a shared resource such as the telephone network or the Internet. It is a communication ...
*
Party line
*
Lec billing
*
Interexchange carrier
An interexchange carrier (IXC), in U.S. legal and regulatory terminology, is a type of telecommunication company, commonly called a long-distance telephone company. It is defined as any carrier that provides services across multiple local access ...
References
*
Communication circuits
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