After much work, the first two nodes of what would become the ARPANET were interconnected between UCLA’s School of Engineering and Applied Science and SRI International (SRI) in Menlo Park, California, on October 29, 1969. The ARPANET was one of the “eve” networks of today’s Internet. Following on from the demonstration that packet switching worked on the ARPANET, the British Post Office, Telenet, DATAPAC and TRANSPAC collaborated to create the first international packet-switched network service.

Via Wikipedia.