public charging network

A public data network (PDN) is a network established and operated by a telecommunications administration, or a recognized private operating agency, for the specific purpose of providing data transmission services for the public.
The first public packet switching network, RETD, was deployed in 1972 in Spain. "Public data network" was the common name given to the collection of X.25 providers, the first of which was DATAPAC in 1976. The International Packet Switched Service became the first commercial and international packet-switched network in 1978. Their combined networks had large global coverage during the 1980s and into the 1990s. These networks later provided the infrastructure for the early Internet.

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