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 ...

, 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 infrastructure and services for public telecommunication. The PSTN is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local telep ...

, 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, ''Private Line'' is a term trademarked by Motorola to describe an implementation of a Continuous Tone-Coded Squelch System (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