It was created in 1978 by a collaboration between Britain's Post Office Telecommunications, and the United States' Western Union International and Tymnet.
[4][5][6] Companies and individual users could connect in to the network, via a PSS (Packet Switch Stream) modem, or an X.25 PAD (packet assembler/disassembler), and a dedicated PSS line, and use it to connect to a variety of online databases and mainframe systems.
By 1984 British Telecom had joined the PSS to the global network and was providing IPSS services to customers.
[7] In 1988 the IPSS directory listed approximately 800 global sites available for connection via X.25.
The network later adopted TCP/IP and provided infrastructure for the early Internet.