Running Cellular Network Infrastructure on Linux Traditionally, much unlike the Ethernet/IP network, classic telecom infrastructure has been running proprietary hardware, operating systems and protocol stacks. In recent years, some Free Software projects have set out to implement some of the related protocol stacks and network elements on top of Linux, including the unrelated OpenBTS and OpenBSC projects, as well as the less known other members of the Osmocom umbrella project: OsmoBSC, OsmoNITB, OsmoBTS, OsmoPCU, OsmoSGSN, OpenGGSN, and many more. As signalling protocols tend to be complex and in many use cases the signalling performance is not super critical, those projects primarily implement the protocol stacks and network interfaces in user-space. This presentation will cover an overview of the many different projects out there, which of the cellular network elements they implement.