OpenBSC, a complete GSM network side implementation, including BSC, MSC, HLR, implemets A-bis and A protocols of GSM network

v.42 bis 协议，sndcp协议压缩标准。sndcp属于3gpp规范-v.42 bis agreement, sndcp protocol compression standard. sndcp are 3gpp specification

OpenBSC implements several MSC components, including the A-bis protocol (the protocol between the BTS and the BSC), AUC, HLR, VLR (both using SQL tables), and a SMS Switching Center. OpenBSC can be accessed using telnet.