By John Dulaney
The Subscriber Identity Module (SIM) is a smart card chip, of the size of a postage stamp, which when inserted in your mobile phone, forms the intelligent source of the various types of communications.
A Smart Card is an integrated circuit card (ICC) and is defined as a miniature card with embedded integrated circuit. The currently available SIM card has 16 to 64 kb of memory, which stores your personal telephone numbers that you call, text messages that you receive or send and other value added services. The memory storage available in your SIM card stores these data or information for you to avail them as and when you require.
One of the third generation mobile phone technologies is called Universal Mobile Telecommunications System (UMTS). A Universal Subscriber Identity Module (USIM) is an application for UMTS mobile telephony running on Universal Integrated Circuit Card (UICC).
UICC is another type of chip smart card used in GSM and UMTs. Unlike SIM, this card has a huge memory space and holds a few kilobytes of data. SIM cards are available on the basis of a subscription on signing a contract with the service provider.
Two SIM cards may also be used in your mobile phone. This has many advantages viz. you could hold two SIM cards in a single mobile phone, featuring pay-as-you-go and pre-paid as well, for your office and personal use respectively.
In most of the cases, the SIM can be removed from the mobile phone, enabling you to carry your mobile subscription and data through different types of mobile phones that you may choose to have along the line of GSM phones available.
It may so happen that the mobile phone with the SIM card in it is misplaced somewhere, stolen or lost. You may be liable to pay a charge to the service provider for issuing the duplicate SIM card to you.
Generally the mobile phones available are 'SIM unlocked' and as such it may be used with any SIM card from any carrier in the world.
The embedded circuitry of the SIM card holds information about the service plan that you have chosen as a subscriber. The information about your current area location (LAI) in the network is also stored by the SIM as network information.
The SIM card in your mobile phone identifies you, by holding an International Mobile Subscriber Identity (IMSI). All GSM and Universal Mobile Telecommunications System (UMTS) network users are uniquely associated with IMSI, and this number is stored in the SIM.
For security purposes, the SIM card features storage of Personal Identification Number (PIN) code, which is a 4-8 digit password chosen by you, and entered each time you wish to gain access to your mobile phone.
In addition to the mobile phone smart cards mentioned above, viz., SIM and USIM, the following are the other types which have application in different network technology:
ISIM - IP International Services Identity Module is a smart card like the SIM, which is applicable in a UICC smart card environment in a 3G (Third Generation Technology) mobile telephone in the IP Multimedia Subsystem (IMS) environment.
R-UIM - The Removable User-identity Module is like a SIM but capable of working with both, in CDMA and GSM phones and networks. The R-UIM fits into any existing GSM phone and is compatible with any GSM SIM.
W-SIM - The Wilcom SIM has been developed by Willcom, which, in addition to the functions of a SIM, provides radio receiver/transmitter facilities as its built-in feature.
Super ghost sim
Product info:
Super ghost sim
- Fully compatible with 3G sims
- Doesn't run down battery life like older versions do
- Switch between sims via the phone's menu!
- Option to auto switch between sims every 1-99 minutes
- use the manual sim selection option if you don't want to auto switch
- allows you to use two sim cards in one phone
- no need to cut your sim card like with similar products
- more convenient than removing your back cover/battery every time you want to swap sim cards
- combine business/personal lines and address books on one handset
- switch between networks easily - no more coverage problems!
- take advantages of cheaper rates from different phone companies
- saves your previous calls, received calls, time and date settings etc.
- new ultra slim design - sits inbetween your battery and
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