Dear, Fahim! Appropriated ciphering algorithm activation is required on MSC also. Without this there is no ciphering at all in your network (because MSC commands to BSC by means of CIPHER MODE COMMAND to start ciphering and indicates the supported algorithms. The BSS then selects an appropriate algorithm, taking into account the MS ciphering capabilities).
It was many complaints from subscribers (without A5/2 support) in our network when it supported A5/2 only. But I didn’t face with mobiles that doesn’t support A5/1.