Telephone plug
A telephone plug is a type of male connector used to connect a telephone to the telephone wiring in a home or business, and in turn to a local telephone network. It is inserted into its female counterpart, a telephone "jack", commonly affixed to a wall or baseboard. The standard for telephone plugs varies from country to country, though the RJ11 "modular connector" has become by far the most common.
A connection standard, such as "RJ11", specifies not only the physical connector, but how it is wired (the "pinout").[1] Modular connectors are specified for the Registered Jack series of connectors, as well as for Ethernet and other connectors, such as 4P4C (4 position, 4 contacts) modular connectors, the de facto standard on handset cables,[2] often improperly[3][4] referred to as "RJ" connectors.
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[edit] History
Historically the telephone was often owned by the supplier and permanently wired in to the telephone line they supplied but as phone markets became more deregulated there was a need for a simple plug-in interface that consumers could use. Many countries initially used their own connectors. For example Bell System companies in the 1960s used a round plug about 40mm in diameter with four prongs about 15mm apart. National connectors remain in service but few are used for new installations.
[edit] List of connections
On a conventional wired telephone, there are 4 connections, each of which may be hardwired, but more often uses a plug and socket:
- telephone line to phone cable
- The wall jack. This connection is the most standardized, and often regulated as the boundary between an individual's telephone and the phone network. (In many homes, though, the boundary between utility-owned and household-owned cable is a jack on an outer wall; all wall jacks in the home are part of the household's internal wiring.)
- phone cable to phone base
- This and further connections is generally not regulated, but instead has de facto standards. It is often 6P4C, which is often RJ11, but may be proprietary or hardwired.
- phone base to handset cable
- handset cable to handset
- The last two (the handset cable) has a de facto standard of a 4P4C connector with straight through cable.
Some of these may be absent:
- Wired telephones may not have a separate base and handset,
- the defining characteristic of wireless telephones is that they do not have a handset cable, and
- the defining characteristic of mobile telephones is that they do not have a phone cable.
[edit] Wiring
A standard specifies both a physical connector and how it is wired. Sometimes the same connector is used by different countries but wired in different ways.
For example, telephone cables in the UK typically have a BS 6312 (UK standard) plug at the wall end and a 6P4C or 6P2C modular connector at the telephone end: this latter may be wired as per the RJ11 standard (with pins 3 and 4), or it may be wired with pins 2 and 5, as a straight through cable from the BT plug (which uses pins 2 and 5 for the line, unlike RJ11, which uses pins 3 and 4). Thus cables are not in general compatible between different phones, as the phone base may have a socket with pins 2 and 5 (requiring a straight through cable), or have an RJ11 socket (requiring a crossover cable).
When modular connectors are used, the "latch release" of the connector should be on the "ridge" side of flat phone wire in order to maintain polarity.
Though four wires are typically used in U.S. phone cabling, only two are necessary for telecommunication. In the event that a second line need be added, the other two are present.
[edit] Compatibility
Different telephone connections are generally compatible with the use of an adapter: the physical connector and its wiring is the primary incompatibility.
See: gallery of telephone adapters.
[edit] List of plugs
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This list is incomplete; you can help by expanding it.
[edit] Modular connectors
- 4P4C and 4P2C for handset cables (often erroneously referred to as RJ9, RJ10, and RJ22)
- 6P2C for RJ11 single telephone line
- 6P4C for RJ14 two telephone lines
- 6P6C for RJ25 three telephone lines
- 8P8C for RJ61X four telephone lines, RJ48S and RJ48C for four-wire data lines, RJ31X single telephone line with equipment disconnect, RJ38X (similar to RJ31X but with continuity circuit)
[edit] Other connectors
- 50-pin miniature ribbon connector for RJ21X, used for up to 25 lines for multiline phones such as the ITT 2564, key telephone systems such as the 1A2 Key System, and PBX systems.
[edit] International standards
- RJ11, by far the most common
- BS 6312, British
- F-010, French
- TAE connector, German
[edit] National standards
- TDO-connector, Austria
- WT-4, Polish National Standard
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WT-4 and RJ11 telephone socket (double system)
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WT-4 telephone plug with RJ11 outlet (adapter)
- WT-4
- RJ11
- Cable holes
Traditionally, the 5th plastic pin disconnects 1 μF capacitor that shorts telephone line while plug is not inserted into socket. In modern makes it does nothing electrical, and capacitor compartment was reused for additional RJ11 socket.
[edit] Legacy
- 600 series connector, Australia
- Protea, South Africa
- SS 455 15 50, Sweden and Iceland
- Telebrás plug, Brazil
- Tripolar plug, Italy
- BTicino 2021 (with or without line interruption), Italy (rare)
[edit] List of countries and territories, with the plugs they use
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This list is incomplete; you can help by expanding it.
This list covers only single line telephone plugs commonly used in homes and other small installations; there are 44 different variations of plugs, including an Israeli version of BS6312 with different internal wiring of the pins, plus of course hard wiring to a junction box with no adapter. Special telephone sets use a variety of special plugs, for example micro ribbon for key telephone systems and the wide array of registered jacks.
- ^ a b c d e f g h i j k l m n o p q r s t u v w x y z Used in older installations
- ^ Used for ADSL
- ^ a b c d e f g Used in newer installations
- ^ Currently the dominant plug
- ^ a b c d e f Often, although incorrectly referred to as "RJ45"
- ^ a b Used for ISDN
- ^ Although other types can also be found
- ^ Used for ISDN, Digital PBX, and office systems
- ^ Used for pre mid-1980's installations
- ^ Same plug used for POTS, ISDN and LAN
- ^ For local battery telephones, not used since approximately 1980
- ^ Also known as R.I.T.A.
- ^ Rarely used today
- ^ Same as the Polish WT-4
- ^ For special use
- ^ Used for ADSL British telephone sockets
[edit] See also
[edit] References
- ^ Semenov, Andrey B.; Strizhakov, Stanislav K.; Suncheley, Igor R. (October 3, 2002). "Electrical Cable Connectors". Structured cable systems (1st ed.). Springer. p. 129. ISBN 3-540-43000-8. "The abbreviation for registered jack, RJ defines a particular wiring scheme of individual wires into outlet contacts. For example, a 6-position outlet may be wired to RJ-11C scheme (one pair), RJ-14C (two pairs), or RJ-25C (three pairs)."
- ^ BICSI (October 7, 2002). "Background Information". Telecommunications Cabling Installation (2nd ed.). McGraw-Hill Professional. p. 88. ISBN 0-07-140979-3. "4-position and 4-contact connectors are used primarily for telephone handset cords."
- ^ Trulove, James (December 19, 2005). "User Cords and Connectors". LAN wiring (3rd ed.). McGraw-Hill Professional. p. 219. ISBN 0-07-145975-8. "This 8-pin modular plug is probably the most subject to name abuse, because it resembles the specialized RJ-45 connector. However, the RJ-45 wiring pattern (which includes an interface programming resistor) is so radically different from that of T568A and B that it really should not be called by that name at all."
- ^ Oliviero, Andrew; Woodward, Bill (July 20, 2009). "Connectors". Cabling: The Complete Guide to Copper and Fiber-Optic Networking (4th ed.). Sybex. p. 294. ISBN 0-470-47707-5. "The RJ (registered jack) prefix is one of the most widely (and incorrectly) used prefixes in the computer industry; nearly everyone, including people working for cabling companies, is guilty of referring to an eight-position modular jack (sometimes called an 8P8C) as an RJ-45."
- ^ "Columbia/Venezuela phone plug". Archived from the original on April 13, 2008. http://web.archive.org/web/20080413045214/http://kropla.com/venezuela.htm.
[edit] External links
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Wikimedia Commons has media related to: Telephone adaptor |
- Telephone plug list — at Steve Kropla's World Wide Phone Guide
- How to install telephone wiring
