A term used synonymously with Electronic Private Automated Branch Exchange (EPABX) and Private Automated Branch Exchange (PABX). Similar to a central office exchange but smaller. A central off exchange can accommodate 10,000 subscribers. PBX systems are typically designed to accommodate from 20 to 10,000 subscribers or station
Private Branch Exchange. A small, privately-owned version of the phone company's larger central switching office.
Residing in an enterprise, a PBX is a piece of equipment that is responsible for switching calls between enterprise users. The PBX allows the users to share a specific number of external phone lines, saving the added cost of having an external phone line for each user.
Piece of telecommunications equipment installed in a company's office, which makes it possible to connect many internal telephone lines to city telephone lines
A Private Branch eXchange (also called PBX, Private Business eXchange or PABX for Private Automatic Branch eXchange) is a telephone exchange that serves a particular business or office, as opposed to one a common carrier or telephone company operates for many businesses or for the general public.
PBX Functions :
the PBX performs three main duties:
Maintaining such connections as long as the users require them. (I.e. channeling voice signals between the users)
Providing information for accounting purposes (e.g. metering calls)
In addition to these basic functions, PBXs offer many other capabilities, with different manufacturers providing different features in an effort to differentiate their products. Common capabilities include (manufacturers may have a different name for each capability):
Telephone history :
Graham Bell (1847-1922) is most famous for his invention
of the telephone. As a teenager of 18, Bell had
been experimenting with the idea of transmitting
speech. In 1874, while working on a multiple telegraph
he developed the basic ideas for the telephone.
mannequins, Telecommunications Museum, Madrid, Spain
Historically a PBX was a company's manual switchboard.
These were gradually replaced by automated electromechanical
and then electronic switching systems, called PABXs
(Private Automatic Branch eXchange).
were distinguished from smaller "key systems"
by the fact that external lines are not normally
indicated or selectable at an individual extension.
From a user's point of view, calls on a key system
are made by selecting a specific outgoing line and
dialing the external number; calls on a PBX are
made by dialing the escape code (usually 9, 0 in
some systems) followed by the external number.
first consumer PBX systems were for the analog telephone
systems, typically supporting four private analog
and one public analog line. They have the size of
a small cigar box or smaller and are inexpensive.
With the pickup of VoIP by consumers, of course consumer VoIP PBXs have seen the light, and PBX functions have become simple additional features of consumer-grade routers and switches.
of recent open source projects (in particular, Asterisk
and SIPfoundry) claim that their initiatives have
finally brought PBXs within the reach of individuals
and small businesses. However, some affordable off-the-shelf
solutions have been available since the beginning
of the 90s.