What is a SIM CARD?

I had never heard of a SIM card before my trip to Thailand. Many international travelers as well as locals use them all the time. They are an inexpensive alternative to long distant roaming fees in addition to being convenient for day to day use. This is how they work-

A SIM card or Subscriber Identity Module is a portable memory chip used in some models of cellular telephones. By simply sliding in the SIM card, you can make your old cell phone a new one. The SIM holds personal identity information, cell phone number, phone book, text messages and other data. It can be thought of as a mini hard disk that automatically activates the phone into which it is inserted.

A SIM card can come in very handy. For example, let's say your phone runs out of battery power at a friend's house. Assuming you both have SIM-based phones, you can remove the SIM card from your phone and slide it into your friend's phone to make your call. Your carrier processes the call as if it were made from your phone, so it won't count against your friend's minutes.

If you upgrade your phone there's no hassle involved. The SIM card is all you need. Just slide it into the new phone and you're good to go. You can even keep multiple phones for different purposes. An inexpensive phone in the glove compartment, for example, for emergency use, one phone for work and another for home. Just slide your SIM card into whatever phone you wish to use.

A SIM card provides an even bigger advantage for international travelers -- simply take your phone with you and buy a local SIM card with minutes. SIM cards can be purchased in airports as well as small markets through out the country of Thailand.

Information gathered from the Wise Geek website http://www.wisegeek.com/

*Side note from Kathy: It is important to note that not all cell phone styles can be fitted for SIM cards