Telephone switchboard
From Wikipedia, the free encyclopedia
A switchboard (also called a manual branch exchange) is a device used to manually connect a group of telephones from one to another or to an outside connection, within and between telephone exchanges or private branch exchanges (PBXs), used in offices and hotels. The user is typically known as an operator.
The electromechanical automatic telephone exchange, invented by Almon Strowger in 1888, gradually replaced manual switchboards in telephone exchanges. Manual PBXs have for the most part been replaced by more sophisticated devices or even personal computers, which give the operator access to an abundance of features. In modern businesses, a PBX often has an attendant console for the operator, with an auto-attendant often avoiding the operator entirely.
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[edit] Operation
The switchboard is usually designed to enable the operator to sit at it. It has a high backpanel 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 are columns of 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. 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 physically ring a telephone. 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 (front key) connects the operator to the cord pair, and a key in the back position sends a ring signal out on the cord (on older manual exchanges). Each cord has a three-wire TRS 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 up on the back panel and the operator responds by placing the rear cord into the jack and throwing the front key forward. The operator now converses with the caller and finds out where the caller would like to be connected to. If it is another extension, the operator places the front cord in the associated jack and pulls the front key backwards to ring the called party. After connecting, the operator leaves both cords "up" with the keys in the normal position and the parties can converse.
[edit] History
Switchboards came into use shortly after the invention of the telephone in 1876. Small towns typically had the operator's switchboard installed in the operator's home so that she could answer calls on a 24 hour basis. In 1894, New England Telephone and Telegraph installed the first battery-operated switchboard on January 9 in Lexington, Massachusetts.
Early switchboards in large cities usually were mounted floor to ceiling. The operators were boys who would scoot up a ladder to connect to the higher jacks. Operators were almost always women until the mid-1960s when men were once again hired. The early "cord" switchboards were often referred to as "cordboards" by telephone company personnel.
As telephone exchanges converted to automatic, or direct dial, service, switchboards remained in use for 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 call. In large cities, there was often a special number, such as 1-1-2, which would ring the long-distance operator directly . In other cities, the subscriber would ask the local operator to ring the long-distance operator.
When calling long distance, the customer often would not have the phone number available, so would simply ask for the name and city of the person desired. The long distance operator would plug into the trunk for the distant city, and the inward operator in the distant city would answer, obtain the number from their local information operator, and ring the call.
Later, with the advent of operator dialing, the operator would plug into a trunk line and dial the area code and operator code for the information operator in the distant city. If the customer knew the number, and the point was direct-dialable, the operator could dial the call. If the distant city did not have dialable numbers, the operator would dial the code for the inward operator, and ask her to ring the number.
After most phone subscribers had direct long-distance dialing, one type of operator served both the local and long distance functions. A customer might call to request help getting through on a number that did not ring, or might be out of order, for instance. If the number was in a distant city, the operator would call the inward operator in the destination city, and ask her to try the number, or to test a line to see if it was busy or out of order.
[edit] Virtual Switchboard
A Virtual Switchboard is an automated system used to connect an incoming caller with an agent or staff member. The virtual switchboard user normally has the option of controlling how incoming calls are routed via a web interface. For example calls could be routed to different destinations according to certain criteria such as the time of day etc.
Interactive voice response (IVR) functionality is also a common feature with Virtual Switchboards. IVR enables incoming callers to a Virtual Switchboard to hear prerecorded announcements. Popular announcements instruct callers to press a number on their key pad to select which department they want to reach (for example, "press 1 for sales, 2 for accounts and 3 for support").
