The evolution of telephony
People were always looking for the most efficient way to communicate remotely. The history of remote communication began with the smoke signals. Later on they were changed by mail, pigeon post, and maritime flags. But probably the greatest innovation was achieved when communication became electrical. The story of telephony began with the invention of the electrical telegraph and later – telephone. It was the radical invention of those times and it changed the way people communicate with each other.
Analog Telephony First, communication was point-to-point and voice was transmitted over analog signals. To establish a call between two people, telephones had to be interconnected by wires. But instead of linking all telephones with each other, a more efficient solution was used.
Phones were connected to the central telephone network mechanism, called a switchboard.
Switchboard Switchboard was a telecommunication system, used to establish telephone calls between subscribers, or between other exchanges.
They were manually controlled by switchboard operators who were responsible for connecting calls between two parties. Mechanical switchboards have set the beginning of the public switched telephone network (PSTN) in the United States in 1878. PSTN was the aggregate of the telephone exchanges, phones and interconnecting facilities that were used to provide phone service to the public.
Even though switchboards enabled more efficient communication, telephone services had one big problem. It was possible to send only one signal over a wire. The price of such connection was very high as each call had to be established manually and a pair of copper wires could not be used for more than one conversation. The investment to set up a telephone network was huge and only large corporations could afford that. But things have changed a lot at the end of 19th century when dial telephone and automatic telephone exchange were invented. Manual switchboards were gradually replaced and communication became faster and more affordable. As a result, wired networks expanded as the demand for telephone services was rising.
Digital telephony In the middle of 20th-century microwave communications appeared, allowing signals to be transmitted over the air in the areas that could not be covered by wires. In addition to this, Bell Laboratories invented the transistor which helped to develop a computer-based electronic switch and set the start for modern electronics. Development of new technologies has gradually transformed analog signals to digital (this process is sometimes called digitization). Digital telephony turned signaling and voice to a stream of bytes and made it possible to send multiple signals over the same circuit. This has increased the call capacity per wire, reduced the cost of the network and improved voice quality. Digital technology and the advent of the personal computer in the 1980s has opened new opportunities in telephony. It became possible to use a computer to initiate phone calls and manage calling process. Computer network started to “gain” similar capabilities to the telecommunication network, just performance to carry the good quality of voice was not sufficient.
VoIP In the mid-1990s, computer network performance has improved and reached a point where it became possible to send a stream of media information across a network connection. Media stream was chopped up into the segments, which were wrapped in an addressing envelope. Due to their origin such computer-based connections were called a packet-switched. The biggest challenge back then was to send a flood of these packets between two endpoints, ensuring two conditions: packets should arrive in the same order in which they were sent, in an appropriate timeframe, and none of the packets could be lost. Since the time those conditions was reached, Voice over IP (VoIP) became a well-known alternative to the standard telephony.
P.S. This post is a part of the book “How to Start and Run VoIP Business” which will be released by the end of 2015. If you found it interesting and would like to receive more information like this, sign up for the newsletter in http://www.runvoipbusiness.com
By Vilius Stanislovaitis VoIP Business Start Consultant, VoIP Softswitch Expert