1964

In 1964 Paul Baran, working for RAND Corporation, conducts a study about the reliability of communication networks, especially about the reliability of the AT&T telephone network in case of a nuclear missile attack.
Paul Barans Study

But AT&T being sure of their expertise didn’t take this study very seriously. About the same time Donald Watts Davies, a British physicist, worked on the same concept of distributed network nodes. However Davies has more luck with his ideas than Baran since he receives public funding as well as funding from telephone companies for his theory.
Davies as well as Baran not only planned on decentralising the communication points, they also planned to split up messages in small blocks or packets. The segmentation of data into small packets, tagged with address of sender and recipient, so they could find their way autonomously across the network, was a requirement for the distributed and decentralised architecture of the internet. Due to the parallel studies of Paul Baran and Donald Watts Davies a general change. Thanks to the parallel studies of Paul Baran and Donald Watts Davies, 1964 saw a paradigm switch in the telecommunications sector from circuit-switched to packet-switched concepts.