Clear telephone conversations have been around since 1876 when  Alexander Graham Bell said “Mr. Watson, come here! I want to see you!”  Since then, the technology has evolved into the digital age. What is important to note, before understanding current technology, is how it worked in the past.

If you go back to the days of the manual switchboard, it is easy to understand how the larger phone system works. In the days of the manual switchboard, there was a pair of copper wires running from every house to a central office in the middle of town. The switchboard operator sat in front of a board with one jack for every pair of wires entering the office.

When someone picked up the handset on his or her telephone, the hook switch would complete the circuit and let current flow through wires between the house and the office. This would light the light bulb above that person’s jack on the switchboard. The operator would connect his/her headset into that jack and ask who the person would like to talk to. The operator would then send a ring signal to the receiving party and wait for the party to pick up the phone. Once the receiving party picked up, the operator would connect the two people together in exactly the same way the simple intercom is connected.

When comparing this to the current age, the role of the human operator was replaced by specialized computer located in the Central Office of telecommunication company or Private Branch Exchange (PBX) in case of a business. If you are calling someone connected to the same office, then the switch simply creates a loop between your phone and the phone of the person you called. If it’s a long-distance call, then the loop between your phone and remote location is created using a long-distance network.

The costs for this network connection, however, have been extremely high. For businesses with multi-site operations, in addition to high connection costs, creation of unity between parties located in separate offices may pose a significant challenge. This leads us into the second part of this series: “How has SIP trunking changed the network?”