SIM Cards
A SIM (subscriber identity module) is an electronic card which securely stores the key identifying a mobile phone service subscriber, as well as subscription information, preferences and text messages. The equivalent of a SIM in UMTS is a Universal Subscriber Identity Module (USIM).
The SIM stores network state information such as its current location area identity (LAI). If the handset is turned off and back on again it will take data off the SIM and search for the LAI it was in. This saves time by avoiding having to search the whole list of frequencies that the telephone normally would. Each SIM is uniquely identified by its ICCID [International Circuit Card ID].
SIM cards identify users uniquely by holding an IMSI.
What is a SIM card?
The SIM (Subscriber Identification Module or Subscriber Identity Module) card - a.k.a. "smart card" - holds all of a subscriber's personal information and phone settings. In essence, it is the subscriber's authorization to use the network. It also holds the phone number, personal security key and other data necessary for the handset to function. The card can be switched from phone to phone, letting the new phone receive all calls to the subscriber's number.
How do SIM cards functions?
The SIM is inside each handset and functions as its digital brain. The authentication and encryption capabilities of the SIM prevent your phone from being stolen and your calls from being eavesdropped on. The SIM's digital memory, which stores information like your rate plan, phone number and service features, also allows you to easily personalize your service and contains user ID and billing information that can be switched between different phones. So, with your SIM card installed, you can make or receive calls personally even when you're using a borrowed phone. Upgrading your phone is as simple as slipping your SIM card into your new phone.
In July 2005, the Finnish government announced that a Citizen Certificate - a government-guaranteed 'electronic identity' included in a SIM card - will be made available to every individual resident in Finland before the end of 2005, allowing mobile phone users to access e-services on the move. The Citizen Certificate has been described as "basically an e-ID card that will be compatible with several hardware devices, such as mobile phones, PDAs, personal computers, Digital TV sets, and public web kiosks".
[1] The first SIM cards with embedded Citizen Certificates have already been made available in selected localities.
The use of SIM card is mandatory in the GSM world, whereas the SIM (RUIM) is not very popular in the CDMA world.
The major SIM card vendors in the market are Axalto, Gemplus, G&D and Oberthur Card Systems.
W-SIM is a SIM card which also integrates core cellular technology into the card itself.
Wednesday, April 26, 2006
GSM Technology
GSM Technology
GSM (Global System for Mobile Communications) leads the world as the fastest growing, most reliable and advanced digital technology available in the marketplace today. GSM provides integrated voice mail, high-speed data, fax, paging and short message services capabilities. GSM customers enjoy secure communications, and GSM offers unparalleled call privacy and fraud prevention. As members of the GSM Global Network, GSM subscribers can use their phones at home, across town, across the continent, or around the world (except for with country specific SIM cards). GSM operates on the multiple spectrum frequency bands used around the world - 1900MHZ, which is used in North America and 900MHz and 1800 MHz for other locations. Different mobile phone networks operate at different frequencies, which means that if you wish to use your mobile phone outside your home country, you generally need a handset that supports multiple frequency bands. Make sure that the celluar phone you are interested in is compatible with the GSM band of the country you will use it in.
As a general Guideline:
Dual-band - A dual-band phone operates at both the 900 MHz and 1800 MHz spectrum. Dual-band works in Europe, Africa, Asia, Australia, New Zealand and much of South America.
Tri-band - A tri-band phone operates on three frequency bands, 900 MHz, 1800 MHz and 1900 MHz, allowing you to use it in Europe, Africa, Asia, nearly all of North America, Australia and New Zealand.
Quad-band - A quad-band phone allows you to roam almost anywhere globally. It covers the 850 Mhz, 900 MHz, 1800 MHz and 1900 MHz frequency ranges. Many countries in South America only have 850 MHz GSM service while both 1900 MHZ and 850 MHz GSM services are supported in the USA. 99% of all countries use the GSM standard. WE believe eventually GSM will be the only cell phone standard in the world.
The GSM network provides the best digital wireless voice quality in the world today.
GSM (Global System for Mobile Communications) leads the world as the fastest growing, most reliable and advanced digital technology available in the marketplace today. GSM provides integrated voice mail, high-speed data, fax, paging and short message services capabilities. GSM customers enjoy secure communications, and GSM offers unparalleled call privacy and fraud prevention. As members of the GSM Global Network, GSM subscribers can use their phones at home, across town, across the continent, or around the world (except for with country specific SIM cards). GSM operates on the multiple spectrum frequency bands used around the world - 1900MHZ, which is used in North America and 900MHz and 1800 MHz for other locations. Different mobile phone networks operate at different frequencies, which means that if you wish to use your mobile phone outside your home country, you generally need a handset that supports multiple frequency bands. Make sure that the celluar phone you are interested in is compatible with the GSM band of the country you will use it in.
As a general Guideline:
Dual-band - A dual-band phone operates at both the 900 MHz and 1800 MHz spectrum. Dual-band works in Europe, Africa, Asia, Australia, New Zealand and much of South America.
Tri-band - A tri-band phone operates on three frequency bands, 900 MHz, 1800 MHz and 1900 MHz, allowing you to use it in Europe, Africa, Asia, nearly all of North America, Australia and New Zealand.
Quad-band - A quad-band phone allows you to roam almost anywhere globally. It covers the 850 Mhz, 900 MHz, 1800 MHz and 1900 MHz frequency ranges. Many countries in South America only have 850 MHz GSM service while both 1900 MHZ and 850 MHz GSM services are supported in the USA. 99% of all countries use the GSM standard. WE believe eventually GSM will be the only cell phone standard in the world.
The GSM network provides the best digital wireless voice quality in the world today.
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