A consequence of international roaming is the exchange of information between providers in different countries. All countries have strict regulations against the export of encryption algorithms and thus GSM works around it. When a user tries to use his phone in say another country, the local networks request the HLR …

Security in GSM :

1. GSM offers several services using confidential information stored in the AuC and in the individual SIM.
2. The SIM stored personal, secret data and in protected with a PIN against unauthorized use.

3. Three algorithms have been specified to provide security services in GSM.

   --> Algorithm A3 is …