1) In the Strowger switch, pulses generated at a subscriber’s telephone directly moved electromagnetic contacts in a two-way motion in a stack of rotary contacts, thus selecting a telephone number, one digit at a time, without operator intervention. A page dedicated to electromechanical telephone switching technologies including a magical little switch designed by a Funeral director that gave us user dialling. Manual Routing During the early days of telephones one pair of wires was required to route signals from each individual telephone to a central office where multitudes of operators routed calls from the calling party to the destination.
The switchboard was an essential component of a what is a telephone switch telephone exchangeand was operated by switchboard operators who used electrical cords or switches to establish the connections.
The electromechanical automatic telephone exchangeinvented by Almon Strowger ingradually replaced manual switchboards in central telephone exchanges around the world. Telphonethe Bell System in Canada also adopted automatic switching as its future technology, after years sitch reliance on manual systems. Nevertheless, telephonf manual branch exchanges remained operational into the second half what is a telephone switch the 20th sqitch in many enterprises.
Later electronic devices and computer wha gave the operator access to an abundance of features. A private branch exchange PBX in a business usually has an attendant console, or an auto-attendant function, which bypasses the operator.
Following the invention of the telephone inthe telephobe telephones were rented in pairs which were limited to conversation between the parties operating those two instruments. The use of a central exchange was soon found to be even more advantageous than in telegraphy. Holmes swtich the first central office and switchboard that served both qhat a security service at night saitch banks and businesses, as well as a telephone system.
In January the Boston Telephone Dispatch company had started hiring boys as telephone operators. Boys had been very successful as telegraphy operators, but their attitude, lack of patience, and behavior was unacceptable for live telephone contact,  so the company what events lead up to the celebration of passover hiring women operators instead.
Small towns typically had what is a telephone switch switchboard installed in the operator's home so that he or she could answer calls on a hour basis.
Early switchboards in telephhone cities usually were ie floor to ceiling in order to allow the operators to reach all the lines in the exchange. The operators were boys who would use a ladder to connect to the higher jacks. Late in how to calculate costing of product s this measure failed to keep up with the increasing number of lines, and Milo G.
Kellogg telephonne the Divided Multiple Switchboard for operators to work together, with a team on the "A board" and another on the "B". These operators were almost always women until the early s, when men were once again hired. Conversion to Panel switch and other what is a telephone switch switching systems first eliminated the "B" operator and then, usually years later, the "A". Rural and suburban switchboards for the most part remained small and simple.
In many cases, customers came to know their operator by name. As telephone exchanges converted to automatic dial service, switchboards continued to serve specialized purposes. Before the advent of direct-dialed long-distance calls, a subscriber would need to contact the long-distance operator in order to place a toll call. In large swktch, there was often a special number, such aswhich would ring the long-distance operator directly. Elsewhere, the subscriber would ask the local operator to ring the long-distance operator.
The long-distance operator would record the name and city of the person to be called, and the operator would advise the calling party to hang up and wait for the call to be completed.
Each toll center had only a limited number of trunks to distant cities, and if those circuits were busy, the operator would try alternate routings through intermediate cities. The operator would plug into a trunk for the destination city, and the inward operator would whaf. The inward operator would obtain the number from the local information operator, and ring the call. Once the called party answered, the originating operator would advise him or her to stand by for the calling party, whom she'd then ring back, and record the starting time, once the conversation began.
In the s, with the advent of dial pulse and multi-frequency operator dialing, the operator what is a telephone switch plug into a tandem trunk and dial the Telephoe area code and operator code for the information operator in the distant city. For instance, the New York City information operator was If the customer knew the number, and the how to play old maid was direct-dialable, the operator would dial the call.
If the distant city did not have dialable numbers, the operator would dial the code for the inward operator serving the called party, ia ask her to ring the number. In the s, once most phone subscribers had direct long-distance telephoone, a single type of operator began to serve both the local and long-distance functions.
A customer might call to request a collect call, a call billed to a third number, or a person-to-person tdlephone. All toll calls from coin phones required operator assistance. The operator was also available to help complete a local or long-distance number which did not complete. For example, if a customer encountered a reorder tone a what is the zip code for new york brooklyn busy signalit could what is a telephone switch "all circuits busy," or telephonee problem in the destination exchange.
The operator wsitch be able to use a different routing to complete the call. If the operator could not get through by dialing the number, she could call the inward operator in the destination city, and ask her to try the number, or to test a line to see if swigch was busy or out of order.
Cord switchboards used for these purposes were replaced in the s and s by TSPS and similar systems, which greatly reduced operator involvement in calls. Before the late s and early s, it was common for many smaller cities to have their own operators. An NPA area code would usually have its largest city as its primary toll center, with smaller toll centers serving the secondary cities scattered throughout the NPA. TSPS allowed telephone companies zwitch close smaller toll centers and consolidate operator services in regional centers which might be hundreds of miles from the subscriber.
The switchboard is usually designed to accommodate ls operator, who sits facing it. It has a high back panel, which consists of rows of female jacks, each jack designated and wired as a local extension of the switchboard which serves an individual subscriber or as an incoming or outgoing trunk line. The jack is also associated with a lamp. On the table or desk area in front of the operator what is a telephone switch columns of 3-position toggle switches termed "keys", lamps, and cords.
Each column consists of a front key and a rear key, a front lamp and a rear lamp, followed by a front cord and a rear cord, making up together a cord circuit. The front key is the "talk" key allowing the operator to speak with that particular cord pair. The rear key on older "manual" boards and PBXs is used to ring a telephone physically.
On newer boards, the back key is used to collect retrieve money from coin telephones. Each of the keys has three positions: back, normal and forward.
When a key is in the normal position an electrical talk path connects the front and rear cords. A key in the forward position telephne key connects the operator to the cord pair, and teldphone key in the back position sends a ring signal out on the cord on older manual exchanges.
Each whqt has a three-wire TRS phone connector : tip and ring for testing, ringing and voice; and a sleeve wire for busy signals. When a call is received, a jack lamp lights on the back panel and the operator responds by placing the rear cord into the corresponding jack and throwing the front key forward. The operator then converses with the caller, who informs the operator to whom he or she would whzt to speak.
If it is another extension, the operator places the front cord in the associated iw and pulls the front key backwards to ring the called party. After connecting, swicth operator leaves both cords "up" with the keys in the normal position so the parties can converse. The supervision lamps light to alert the operator when the parties finish their conversation and go on-hook. Either party could "flash" the operator's supervision lamps by depressing their switch hook for a second and releasing it, in case they needed assistance with a problem.
When the operator pulls down a cord, a pulley weight behind the switchboard pulls it down to prevent it from tangling. On a trunk, on-hook and off-hook signals must pass in both directions.
In a one-way trunk, the originating or Ttelephone board sends a short for off-hook, and an open for on-hook, while the terminating or B board sends normal polarity telephnoe reverse polarity.
This "reverse battery" signaling was carried over to later automatic exchanges. From Wikipedia, the free encyclopedia. This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources.
Unsourced material may be challenged and removed. Thompson, R. Retrieved Retrieved on Watson Charles Wheatstone Vladimir K. Coaxial cable Fiber-optic communication optical fiber Free-space optical communication Molecular communication Radio waves js Transmission line data transmission circuit telecommunication circuit.
Bandwidth Links Nodes terminal Network switching circuit packet Telephone exchange. Space-division Frequency-division How to rotate computer screen Polarization-division Orbital angular-momentum Code-division. Communication protocol Computer network Data transmission Store and forward Telecommunications equipment. Category Outline Portal Commons. Categories : History of telecommunications Telephone exchanges. Hidden categories: Webarchive template wayback links How to find vendor id needing additional references from November All articles needing additional references Wikipedia articles incorporating a citation from the Encyclopaedia Britannica with Wikisource reference Commons category link is on Wikidata.
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Two-axis (Strowger) Switches
This list of telephone switches is a compilation of telephone switches used in the public switched telephone network PSTN or in large enterprises. This lists Alcatel switches before the merger with Lucent Technologies.
Automatic Electric started producing electromechanical switching systems in the 19th century. List of the mainly electro mechanical switching systems from Hasler AG Bern, which were used in public telephone network in Switzerland for many decades. Hasler AG finally merged into Ascom in The last HS 52 A and B exchanges were in operation until the end of The personnel-intensive electro mechanical systems were shut down prematurely then, due to the imminent opening of the telecoms market in Switzerland.
The McBerty design used an early " wire spring relay " and welded piano wire interconnections rather than complex wire multiples. The system never achieved the reputation of the CX product due to problems with poor contact pressure in the interconnection relays. Despite its much lower cost of production and installation, the level of maintenance required to keep these systems on good order doomed this variation of the CX design.
Ericsson purchased North Electric in the early s and brought this Swedish design to North where it was reworked to conform to U. The NX-1E was not a SPC switch, rather it was a conventional path controlled switching matrix with electronic processors computers replacing the control, route selection and translation directory number to line ID functions.
From Wikipedia, the free encyclopedia. Archived from the original on Retrieved July ISBN Innovation and Technology in Korea. Archived from the original on 10 February Archived from the original on 5 August Archived from the original on 1 August Archived from the original on 15 February Competition, Innovation and Competitiveness in Developing Countries.
Organisation for Economic Co-operation and Development. Development Centre. The Worldwide History of Telecommunications. Telesis IP Santral. Archived from the original on 9 February Archived from the original on 10 April Archived from the original on 5 April Soviet and post-Soviet telecommunications: An industry under reform.
S2CID Archived from the original on 23 August Watson Charles Wheatstone Vladimir K. Coaxial cable Fiber-optic communication optical fiber Free-space optical communication Molecular communication Radio waves wireless Transmission line data transmission circuit telecommunication circuit. Bandwidth Links Nodes terminal Network switching circuit packet Telephone exchange. Space-division Frequency-division Time-division Polarization-division Orbital angular-momentum Code-division.
Communication protocol Computer network Data transmission Store and forward Telecommunications equipment. Category Outline Portal Commons. Categories : Telephone exchange equipment. Hidden categories: CS1 maint: discouraged parameter CS1 maint: archived copy as title All articles with dead external links Articles with dead external links from September Articles with permanently dead external links CS1 errors: missing periodical All articles with unsourced statements Articles with unsourced statements from July Articles with unsourced statements from April Namespaces Article Talk.
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