telecommunications Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electronic means, typically through cables, radio waves, or other communication technologies. These means of ...

, 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 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) is the aggregate of the world's telephone networks that are operated by national, regional, or local telephony operators. It provides infrastructure and services for public telephony. The PSTN consists o ...

, 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 oth ...

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 (''telecommunication'') between two or more points without the use of an electrical conductor, optical fiber or other continuous guided med ...

, ''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. It is sometimes referred to ...

(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 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")

References

* Communication circuits {{telecomm-stub

Types

See also

References