OpenBSC is the current name for a software program that started with the name bs11-abis.

WWhat is OpenBSC

It is a BSC (Base Station Controller) side implementation of the A-bis protocol, as implemented in the GSM Technical Specification 08.5x and 12.21. It implements a minimal subset of the BSC, MSC and HLR. It does not implement ant of the interfaces (like the A and B interfaces) between the higher-order GSM network components.

The goal of the project is to

• provide a basis for experimentation and security research with GSM from the network side
• document, publicized and point out any security related issues that we find as part of that
• learn more about GSM networks on a lower level, particularly the practical aspects with real-world equipment

http://bs11-abis.gnumonks.org/trac/wiki/OpenBSC