Public data network

"Public data network" was the common name given to the collection of X.25 providers, the first of which were Telenet in the U.S. and DATAPAC in Canada (both in 1976), and Transpac in France (in 1978).

In communications, a PDN is a circuit- or packet-switched network that is available to the public and that can transmit data in digital form.

[1] Access to a PDN generally includes a guaranteed bandwidth, known as the committed information rate (CIR).

[6] Today, the term may refer not only to Frame Relay and Asynchronous Transfer Mode (ATM), both providing PVCs, but also to Internet Protocol (IP), GPRS, and other packet-switching techniques.

[10] Telenet adopted X.25 protocols shortly after they were published in 1976 while DATAPAC in Canada was the first public data network specifically designed for X.25, also in 1976.

[11] Many other PDNs adopted X.25 when they came into operation, including Transpac in France in 1978, Euronet in the EEC in 1979, Packet Switch Stream in the United Kingdom in 1980, and AUSTPAC in Australia in 1982.

[17][18][19] Over time, other packet-switching technologies, including Frame Relay (FR) and Asynchronous Transfer Mode (ATM) gradually replaced X.25.