Data
SIM cards store network-specific information used to authenticate and identify subscribers on the network. The most important of these are the ICCID, IMSI, Authentication Key (Ki), Local Area Identity (LAI) and Operator-Specific Emergency Number. The SIM also stores other carrier-specific data such as the SMSC (Short Message Service Center) number, Service Provider Name (SPN), Service Dialing Numbers (SDN), Advice-Of-Charge parameters and Value Added Service (VAS) applications. (Refer to GSM 11.11)
SIM cards can come in at least two capacity types: 32 KB and 64 KB. Both allow a maximum of 250 contacts to be stored on the SIM, but while the 32 KB has room for 33 Mobile Network Codes (MNCs) or "network identifiers", the 64 KB version has room for 80 MNCs. This is used by network operators to store information on preferred networks, mostly used when the SIM is not in its home market but is roaming. The network operator that issued the SIM card can use this to have a SIM card connect to a preferred network in order to make use of the best price and/or quality network instead of having to pay the network operator that the SIM card 'saw' first. This does not mean that a SIM card can only connect to a maximum of 33 or 80 networks, but this means that the SIM card issuer can only specify up to that number of preferred networks, if a SIM is outside these preferred networks it will use the first or best available network.
Read more about this topic: Subscriber Identity Module
Famous quotes containing the word data:
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—Susan Sontag (b. 1933)