Thursday 14 July 2011

How Does a SIM Card Work


  • SIM cards are the most important part of a cell phone that runs on a GSM network. They enable the phone to receive signal from a mobile phone company. Many people who have phones that accept SIM cards find it extremely easy to simply swap out their SIM card for a new SIM card when in a different country.

What is a SIM Card?

SIM cards are formally called Subscriber Identity Module cards. While the first SIM card appeared in 1991, they have been seeing an increase in use due to their ease and their simple design. When compared with a phone that uses CDMA technology, phones that have SIM cards in them offer lower prices and lower rates, especially outside of the United States. When you are traveling to a foreign country, all that you need to do in order to use your GSM, SIM-card enabled phone is to purchase a new SIM card that works for the country that you are in and add credit to it.

Using a SIM Card

When you open up the back of a phone that is equipped with a SIM card, you will see the card tucked into the phone. Usually, the card is tucked behind the battery. SIM cards are also great because they can be used with any handset that accepts them. For example, if your cellular phone breaks and you are unable to make calls from it, but still have an active SIM card, you are in luck. Just take your SIM card out of the old phone and plug it into a new phone and you will have full service. SIM cards are encoded with information about the carrier that you are using, as well as information like your address book. Having information like this on a SIM card will allow you to make a fast and simple switch over to another phone on the same carrier, or to switch carriers completely.

Other SIM Card Uses

Some phones with SIM cards may accept memory cards on their own, however, on most phones, the SIM card is your memory card. All the information that you need is on the phone itself, so you don’t have to download all your numbers when you want to switch phones, and you don’t even need to worry if a certain phone will work with your SIM card. Some phones may need to be unlocked for service with a specific carrier and you may receive a different SIM card, but otherwise you should have no problems using the phone.


SIM cards are a great solution for anyone who likes to change phones or carriers or who travels internationally. They are a quick and easy solution to prevent borders, carriers or locked-down phones from slowing you down. SIM cards keep all of the information that is needed right on your phone. There is no need to constantly back up or write down all the numbers on your phone, and you will never have to worry about outrageous bills when calling overseas when you purchase a local SIM card for your phone.