SIM Card Definition


SIM cards are offered by 600 providers and are used in over 200 countries worldwide. There are over one billion SIM card users worldwide as of 2010, according to AT& SIM cards enable you to use multibrand phones, which lets you continue your service almost anywhere on the globe.

What is a Sim Card?

  • Subscriber Identity Module cards (SIM) are used by various phone companies to supply wireless service through cellular handsets. These cards are supplied as both prepaid and contract and range in price from $2 to $20, depending on the network that supplies them. SIM cards are often referred to as SIM chips or phone chips.

What do They Look like?

  • SIM cards are small rectangular data chips. They have a number printed on the front which is called the SIM number and copper contacts on the back. When purchased, they are usually embedded in a plastic rectangular, credit card sized card. Also on the front of the SIM card will be the initials of your wireless provider or your wireless provider's logo. This means that the SIM card can only be used with the provider on the emblem.

Who Uses SIM Cards?

  • Any network that is considered to be a Global System for Mobile Communications (GSM) provider supplies SIM cards. These SIM cards can be programmed to work regionally, nationally or internationally. They are also supplied by CDMA providers, to enable certain handsets to be used overseas, such as BlackBerrys and iPhones.

What are They Used For?

  • SIM cards store valuable data about your Wireless Service and your handset. They contain 12 kb of external memory, which is mostly used to store contacts and save text messages. You can use SIM cards in any handset that has a SIM card slot. The only restriction, is that you can only use your network provider's SIM card in their own handsets.

How Are They Used?

  • Once you sign up to wireless service with a GSM provider, you will be given a SIM card. You can purchase a contract SIM card from a phone store, electronics store or retail store. If you're purchasing a prepaid service, you can buy a prepaid package, which will include your SIM card and handset. If you decided to go with a contract phone, your SIM card will already be programmed with all of your account details when you receive it. However, if you've gone with the prepaid option, you have to activate the SIM card before use. This can be done by calling customer service or activating it online.

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  • Photo Credit sim card image by Renato Francia from
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