“Anyway, I am sure that between transcoder and mobile, it is impossible for another mobile to hear another conversation. You have ciphering activated, right ?”.
I am not sure but what about if no encryption is used by a5/0 in the network,is it able to listen to that frequency channel. One day one guy told us that he had heard several times telephone calls on his Shortwave (SW2) radio so I wonder if this is possible and at that time our network was using A5/0(encryptionless), after several months we received an email from GSMworld saying to move out from A5/2 and to move either to A5/1 or a5/0 encryptionless. Because some hackers have demonstrated in very short time that they are able to crack that alograthim for the voice traffic.
Anyway I didnt understand your last paragraph?”Therefore, the Abis or the BSC are probably not responsible for the problem.” Do you mean the problem is not related to the BSC? or do you mean the problem is within the BSC?