Erlang is a programming language designed at the Ericsson Computer Science Laboratory. Open-source Erlang is being released to help encourage the spread of Erlang outside Ericsson. We are releasing free of charge: The entire source code of the current Erlang system. Extensive libraries of code for building robust fault-tolerant distributed applications. All with documentation. All the above software has been battle tested in a number of Ericsson products, for example AXD301 (ATM switch).