PSTN (Public Switched Telephone Network) – public telephone networks originally intended only for voice communication. Today, the network includes not only telephone lines, but also cellular networks, cable, fiber-optic and satellite systems, and switching centers.
Principles of operation
PSTN is a huge number of points around the world where switches are located. These switches are nodes that provide communication between two points within the same network. A call is considered fixed when the signal passes through all the necessary switches and is transmitted to a specific telephone line.
Currently, PSTN is used to connect to the Internet. The speed of such a connection is relatively low – no more than 56 Kbit/s. A traditional modem of an outdated model is connected to the telephone line. Today, this type of connection is practically not used, since modern communication formats offer more advanced connection types with higher connection speed and quality.
Over time, PSTNs have been improved. Analog signals and manual control were replaced with automated switches, and then with digital switching, but the connection did not return to its former popularity.