An International Mobile Subscriber Identity or IMSI ( /ˈɪmziː/) is a unique identification associated with all GSM, UMTS and LTE network SIM cards. It is stored as a 64 bit field and is sent by the phone to the network. It is also used for acquiring other details of the mobile in the Home Location Register (HLR) or as locally copied in the Visitor Location Register. To prevent eavesdroppers identifying and tracking the subscriber on the radio interface, the IMSI is sent as rarely as possible and a randomly-generated TMSI is sent instead.
The IMSI is used in any mobile network that interconnects with other networks. This number is provisioned in the phone directly or in the R-UIM card (a CDMA analogue equivalent to a SIM card in GSM).
An IMSI is usually presented as a 15 digit long number, but can be shorter. For example MTN South Africa's old IMSIs that are still being used in the market are shown as 14 digits. The first 3 digits are the Mobile Country Code (MCC), and is followed by the Mobile Network Code (MNC), either 2 digits (European standard) or 3 digits (North American standard). The length of the MNC depends on the value of the MCC. The remaining digits are the Mobile Subscription Identification Number (MSIN) within the network's customer base.
The IMSI conforms to the ITU E.212 numbering standard.
Read more about International Mobile Subscriber Identity: Examples of IMSI Numeric Presentation, IMSI Analysis, Home Network Identity
Famous quotes containing the words mobile and/or identity:
“From three to six months, most babies have settled down enough to be fun but aren’t mobile enough to be getting into trouble. This is the time to pay some attention to your relationship again. Otherwise, you may spend the entire postpartum year thinking you married the wrong person and overlooking the obvious—that parenthood can create rough spots even in the smoothest marriage.”
—Anne Cassidy (20th century)
“One of the most highly valued functions of used parents these days is to be the villains of their children’s lives, the people the child blames for any shortcomings or disappointments. But if your identity comes from your parents’ failings, then you remain forever a member of the child generation, stuck and unable to move on to an adulthood in which you identify yourself in terms of what you do, not what has been done to you.”
—Frank Pittman (20th century)