Erlang is a functional programming language used for implementing very large scale, real-time, concurrent, industrial applications.
Erlang is used in Ericsson products such as AXD301, DWOS, A910, and ANx. It is designed for building phone switches that are complex and reliable --- hundreds of thousands of lines of code, and less than 3 minutes of downtime in one year of operation.
Erlang has been used to control several very large scale (i.e. hundreds of thousands of lines of source code) telecommunications switching system products which are marketed world wide by Ericsson today. It has also been used to implement countless prototypes and experiments.
Ericsson is one of the world's largest manufactures of telecommunications equipment. Ericsson is active in more than 100 countries and has about 80,000 employees.