What Is A PBX Telephone Switchboard

A telephone exchange, also called PBX (Private Branch Exchange Private Branch switching) is a private telephone exchange that usually belongs to a company, which allows connections between internal phones and connect to the PSTN (Public Switched Telephone Network) to via trunk lines. Basically, a telephone can be PBX or IP PBX, being able to hire both a telephone company service Centrex PBX emulation.
Features
A telephone exchange or PBX is an automatic switch that normally attends a private office, private organization or a business and to interconnect the internal telephones in addition to handling calls via trunk lines of the public telephone companies. Mostly used the generic term extension to refer to any internal telephone device, such as telephones, fax machines or modems.
The telephone is a basic component in the communications infrastructure of a company. Currently, the telephone exchange PBX equipment is no longer limited to large companies and is used increasingly in medium and small enterprises and in many homes.
Type
There are basically two types of telephone exchange or PBX:

    PBX is a telephone connected directly to the public telephone network PSTN via trunk lines that run autonomously both internal and external calls (incoming and outgoing). Generally belongs to the company that has installed and not the telephone company.
    IP PBX (also called VoIP PBX) IP PBX is a telephone equipment designed to provide communication services over data networks via the Internet, using VoIP (Voice over IP, Voice over IP).
Currently most include PBX IP PBX functionality, allowing both to operate through the data networks such as via PSTN.
Virtual PBX
Telephone companies offer the service simulated PBX, which is that the public telephone exchange zone is configured such that the lines that reach the customer appear to function as a PBX phone system, with each extension of a pair of wires connects to the telephone company's central. Thus, the telephone company owns and manages all the communications equipment and software necessary to implement the service, and no switching equipment is located on customer premises, which only provides the service. Sometimes operators offer this service under the name or similar unique phone number.
There is the possibility of contracting with the telephone company service emulation PBX IP PBX or PBX:

    Centrex (also called PBX or Hosted PBX Virtual): equivalent to a PBX phone system. The term comes from Central Centrex exchange (clearinghouse).
    IP Centrex (also called Virtual IP PBX or Hosted IP PBX) functionality equivalent to an IP PBX phone system.