Telephony is a science that allows the transmission of voice, data, and video or image signals. Before the telephony era, this was done by primitive and inefficient forms. As telephony advanced, transmission speeds increased to what we now know as real-time.

From the moment the telephone was invented and for at least a century, the term "telephony" was used to describe the business itself that was provided by the telephone companies.

However, as telephony became more complex, the term evolved into "telecommunications" during the 1980s. This term was also used to express that the telephone companies could transmit more than just voice. Stock values also saw a great increase as the telecom industry grew.

During the 1990s, the telecommunications expanded even more when computer companies entered the telecom industry. For the computer companies, the term "telephony" was reinstated as it referred to the telephone incorporated into a workstation. This determined that users could have all the telecom services in their workstations, coupled with other desktop functions.

This section provides a brief history of the telecommunications industry from the invention of the telephone up to the changes implemented during divestiture that shaped the industry as we know it today.