Extension (telephone): Difference between revisions

Revision as of 02:21, 3 April 2007

Revision as of 01:36, 19 April 2007

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A '''telephone extension''' is an internal [[telephone line]] attached to a [[PBX]] or [[Centrex]] system. The PBX operates much as a community switchboard does for a geographic [[telephone numbering plan]] and allows multiple lines inside the office to connect without each phone requiring a separate outside line. In these systems, a dialer usually has to dial a number (typically 9) to tell the PBX to connect with a landline (also called DDCO) to dial an external number. Within the PBX, the user merely dials the extension number of the person. Each phone line may be extended up to a fixed maximum. Since not all users dial out at the same time, it is cheaper to install the PBX than for each phone to have its own private landline.

==Reasons to use extensions==

Since not all users dial out at the same time, it is cheaper to install the PBX than for each phone to have its own private landline. Extensions can be used to save money by lowering the number of [[trunking|trunk lines]] that the company must pay the phone company to use<ref>Newton, H: "Newton's telecom dictionary", page 901. CMP books, 2004</ref>. Extension to extension calls can be made and kept within the company for security reasons. Extensions also make it easier for a worker's phone number to move with them if they change offices in the building. Extensions also allow a great deal of personalized information to be captured by the PBX or a phone recorder to be used to optimize resources. [http://www.versadial.com/call_recording_terms.html#extension]

==External links==

*[http://www.phonecabling.co.uk/services_tel.html Phone Cabling]

==References==

[[Category:Telephony equipment]]

<references/>

[[Category:Telephony equipment]]

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