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as another. In middle 20th century telephone jargon, the first telephone on a line was a "Main
Station" and subsequent ones "Extensions" or even called as intercom. Such extension phones allow making or receiving calls in different rooms, for example in a home, but any incoming call would ring all
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can extend local network access anywhere in the world. In either system, an off-premises extension is reachable from within the same enterprise simply by calling its extension number directly; for inbound and outgoing calls, it functions as if it were located at the main place of business.
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is cheaper than giving each phone its own private landline. Extension to extension calls can be made and kept within the company for cost or security reasons. Extensions make it easier for workers to bring their
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extensions and any one extension being in use would cause the line to be busy for all users. Some telephones intended for use as extensions have built-in
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and allows multiple lines inside the office to connect without each phone requiring a separate outside line. In these systems, one usually has to
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for a small business may offer two to five lines, lamps indicating lines already in use, the ability to place calls on '
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makes the creation of off-premises extensions inexpensive and trivial, as broadband
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may request the number of the desired extension or the call may be completed with
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system. The PBX operates much as a community switchboard does for a geographic
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data to be captured by the PBX or a phone recorder for cost control. A
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to connect the extension to the main enterprise system.
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Since not all users dial out at the same time, sharing
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