Apr 11, 2008 · IMSI. SIM cards are identified on their individual operator networks by holding a unique International Mobile Subscriber Identity. Mobile operators connect mobile phone calls and communicate with their market SIM cards using their IMSI. Authentication key (Ki) The Ki is a 128-bit value used in authenticating the SIMs on the mobile network. A SIM stores necessary credentials to identify itself and authenticate to the network, including a symmetric secret key KI (key identier), a serial number ICCID (Integrated Circuit Card ID) and a unique user number IMSI (International Mobile Subscriber Identity). GSM Authentication and Encryption.
News. Camel Wireless is providing international SIM cards that offer free roaming in the USA, in addition to another 50 plus countries. The offer is said to be built on what is called a Dual IMSI SIM, and each SIM card has two identities, a +44 UK mobile number and a +1 USA mobile number.