Once upon a time the flagship product of the Erlang world was the AXD301, an phone switch from Ericsson sporting 1-2 million lines of highly complex Erlang code. This product was supposedly capable of achieving service availability levels of "nine nines", i.e. 99.9999999% reliability. This is, even by telecom standards, insanely high. In this talk, you will hear about this, what was actually achieved, and how it was done.

The talk will not be about software architecture, testing or "methods to ensure quality", but rather ruminations about debugging in general and the unique opportunities for power debugging offered by the Erlang virtual machine.