CXtec Knowledge Base

PBX

A private branch exchange (PBX) is a telephone network inside a business that switches calls between various users on internal phone lines while also allocating a limited number of external lines among these users. A PBX helps cut company expenses because each individual user does not need a line running to the telephone service provider's main office. The PBX is run independently of the telephone company, so the service provider is not responsible for any required maintenance. PBXs initially utilized analog technology, but currently, they have upgraded to a digital signal; the digital data is changed to analog when calls are made outside the facility on the local loop via traditional landline.

A PBX is comprised of:

• Telephone trunk, or a bundle of lines, that end at the PBX.
• Computer with enhanced memory to control the call switching within the PBX in addition to calls coming in and leaving.
• Network of lines within the PBX.
• Interface (e.g., console, switchboard) for a human operator.

Depending on the size of a business, it may be more logical to go an alternative route instead of a PBX. Options include:

• Centrex service, in which a cluster of lines located at the telephone service provider's headquarters is leased.
• Key telephone networks.
• Primary rate Integrated Services Digital Network, which is recommended for small operations.

PBXs are manufactured by a number of major telecommunications brands such as:

• Lucent Technologies
• Northern Telecom (NORTEL)
• Rolm/Siemens
• NEC
• GTE
• Intecom
• Fujitsi
• Hitachi
• Mitel

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