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