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SIM stands for subscriber identity module
or subscriber identification module. It is a small plastic card
with some metal connectors and an integrated circuit inside. The
integrated circuit is not visible as it is enclosed in moulded
plastic on the outside for protection from damage. The SIM card
device is unique for each mobile number or as rightly called-
international mobile subscriber identity.
The primary purpose of the SIM card is to
store an international mobile subscriber identity along with
it's unique key i.e. a set of characters - Similar to passwords.
This combination of key and IMSI helps the SIM to authenticate
and communicate with the cellular network to receive and send
data and calls directed towards the mobile number associated
with the SIM card. SIM cards also store a PIN and PUK code which
is used for blocking SIM services and to avoid misuse.
Initially SIM cards when introduced were
the size of credit card but were later reduced to that of finger
nail and now to even smaller sizes. The first SIM cards were
introduced in 1991 and later in 1996 they were re-introduced as
mini-SIM which was much smaller and convenient. This was
followed by introduction of smaller Micro-SIM in 2003 and even
smaller Nano-SIM in 2012.
The advantage of using SIM cards was that
they allowed one to change mobile devices and handsets without
loosing their mobile subscriber identity or simply mobile
numbers. Every mobile handset on GSM network needs to have a SIM
card in order to work; unlike in case of CDMA handset where in
the SIM information is stored in the device itself.
All SIM cards contain a string of an
eighteen to twenty digits printed often on their back. This 18
to 20 digits number is the SIM number unique to the SIM. It is
possible to locate and find a lot of information about the SIM
card from this number. Using this SIM number one can find the
purpose of the SIM and also the location of SIM issue and its
issuing cellular network company name.
However it is not possible to find the
exact location of the SIM card from this number alone, if the
SIM is not inserted into any mobile device. SIM card in itself
does not transmit or receives any signal when not inserted into
any mobile device or handset. In order to track the exact
location of the SIM number- one needs to find out about the
cellular network operator which issued the SIM card and contact
them with the SIM number or mobile subscriber number to help
with the trace of the location and owner.
As a preventive measure it is always
advisable to note down the SIM number and mobile handset IMEI
number in a page of paper and store it in a safe place. It is
useful in case of unfortunate events like theft or losing
mobile, when a complain for recovery needs to be lodged with
mobile operator company and police to recover the phone and
track its location. |
