PBX - Private Branch Exchange:
  • It is a private telephone network used within a company or organization. The users of the PBX phone system can communicate within their company or organization and the outside world, using different communication channels like Voice over IP, digital or analog.
  • It is owned and operated by enterprise rather than the telephone company.
  • A PBX is made up of both hardware and software and connects to communication devices like telephone adapters, hubs, switches, routers and of course, telephone sets. 

     Functions of PBX:
    • It allows use of more than one telephone line in an organization, and management of outgoing and incoming calls. 
    • Splitting of one single phone line into several internal lines, which are identified through three or four-digit numbers called extensions, and switching calls to the appropriate internal line. It allows all departments to be reached through one single phone number.
    • It allows free phone communication within the organization. 
    • Automation of response to calling customers with IVR (interactive voice response) whereby the system can automatically direct users to the most appropriate line through voice menus. It is the kind of feature where, as a caller, you hear things like "Press 1 for the Finance Depart, Press 2 for complaints..."
          Types of PBX:
         - Traditional PBX:
    • It is a landline based technology. 
      • With a traditional PBX, you are typically constrained to a certain maximum number of outside telephone lines (trunks) and to a certain maximum number of internal telephone devices or extensions. 
        • User need to install these analog lines in order to use these services.
          • These are very expensive.

               - IP PBX:

          • The difference between traditional and IP PBX is that it a uses digital signals and you need to install it in your system.
          • It uses VoIP technology within it. 
          • It is easier to setup, as it uses ethernet cables for the connection, once you made connections no need to rewind the wires.
          • Digital Receptionists, 
          • It is also expensive but better to be used for large businesses.
          • Remote workers can be connected.
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               - Hosted PBX:
          • It is also uses VoIP technology but it is a cloud based system, no need of installation, access through internet and user need to pay monthly installation.
          • It is easy to setup through ethernet cables and also can be accessed by using mobile phones with the business number.
          • Remote workers can also be connected.
          • It will turn phone calls into data packets and send them over a network.
          • It uses single network for entire data and phone calls and a central server.
          • It is best for small businesses.
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               - Virtual PBX:
          • It is owned and maintained by VoIP service provider.
          • It is best suitable for the business having very less(may be 10) employees.
          • It is simple and having limited cost .
          • It has features such as unlimited calling, voice call, call forwarding but it has a time limit constraint and does not have internet access and conference call.