The PBX

By Raul Bernardino

Introduction:

Nowadays, the networks and internet technology is growing faster. The companies, organizations, governments, and the institutions are using these technologies to connect, communicate, coordinate and collaborate (four sees or 4Cs) in their information sharing among themselves or shared them between the public audiences within cross border information platforms’. The internet communication facility, allows everyone to share their expertise, experiences, knowledge, information, and also to be able to interact within one and another without having any limitation; the accessibility and reliability of the data sharing information and knowledge over networks are to ensure that everyone has same opportunity to access and convene same bits of the information. The information and knowledge has to be reliable and accessible at any time and from anywhere. Therefore, it is important enabling this trend of connectivity’s within an existing networks with internet telephony.  

“The real time interactive audio and video over internet is called internet telephone or internet video call. This is similar to the traditional telephone call which is using telephone circuit and switches”, Kurose J. and Ross K., (2010, P. 627). For example, establishes voice or video calls from PC to PC or from PC to the normal telephone switches voice calls. Other examples are using Skype to call from PC to PC or PC to normal telephone networks, net meeting, go to meeting, and other polycom products such as video and audio conferences.

The PBX stands for private branch exchange. That is a telephone system, where within one office shares the public switched telephone network (PSTN) lines. It can be one or more telephone lines that are coming from telecom provider to the office and the office is sharing those resources among the end users within one office or between branch offices. For instance, four PSTN lines from telecom operator to the office; these PSTN lines can be divided into one dedicates line for the official fax mail machine and other three PSTN lines are connected through the PBX trunks in which to ne shared within the rest of the team. One of PBX trunk shows in the below picture:

Each team member can be reached by extension phones. The extension phones, usually has two to four digits depends on the PBX configuration. The extension phones are also connected to the PBX trunks. One of extension as it shows in the below picture:

The extension phones are enabling team member to make a communication internally or establish a communication within branch offices without have any cost.

The PBX is referring to the PABX and EPABX. The PABX stands for private automatic branch exchange while EPABX stands electronic private automatic branch exchange.

Since 1990, there were developments in the PBX technology. They are focusing on the packet switching. The companies, organization, government, and institutions are using packet switched for the data communication. It attempts to use as telephone calls and later it calls VoIP (Voice over IP). The ISDN also another development in that time, whereas can make a conference call, call forwarding, and caller ids.

The technology between LAN and traditional telephone networks are PBX and router. These two technologies can become exchange switch from normal telephone call to the VoIP or from VoIP to normal telephone network.  For instance, by is using the Skype whereas to make a call from PC to PC or from PC to normal telephone network. The PBX has to add digital trunks in which to enable the connection between router and voice lines. As it shows in below diagram:

The PBX functions are as follows: To establish a communication between two parties or more and it is including ensuring that the line is free or busy. To maintain the connection as it require. To disconnect the connection as it require. To provide the information’s such as telephone bills.

References list:

1.     Kurose, J.F. & Ross, K.W. (2010) Computer Networking: A Top-Down Approach. 5^th ed. Boston: Addison Wesley

2.     Business telephone system, [Online]. Available from: http://en.wikipedia.org/wiki/Private_branch_exchange#Private_branch_exchange   (Accessed: 6 July 2013)

3.     Cisco 3640 Router - PBX Interoperability: Nortel Meridian Option 11 Rel. 24 PBX with Analog FXS and FXO interfaces to an MGCP Gateway, [Online]. Available from: http://www.cisco.com/en/US/docs/voice_ip_comm/cucme/pbx/interop/notes/210514nt.pdf (Accessed: 6 July 2013)