If your service provider uses the GSM network, your phone must use a Sim card (subscriber identity module).This is the removable chip located behind the battery that has your account information stored on it.
What are the advantages to having a Sim card?
1. Sim cards allow the user to use multiple phones with just one account.(Of course you will only be able to use one phone at a time).
2. Sim cards also allow the user to store contact information on the chip itself. Most phones are defaulted to store the information to the phone only. You must go into your settings (contacts for Nokia users) and copy the information to the Sim card.
This comes in very handy if your phone decides one day to stop working.
3. You can download your contact information to your computer by simply purchasing a Sim card reader (.generally only $10-$15).
*Note - Sim card readers will not allow you to download ringtones, wallpaper or any other accessories to your phone.
What are the disadvantages?
1. You can only get one number per phone. You will not be able to take advantage of the multi-line capability of your phone.
2. Sim cards can go bad. They generally cost about $10 to replace and are not covered under warranty. This will require a trip to your local dealer.
3. If you forget to lock your phone or sim card, anyone with a GSM phone can steal your contacts by simply placing your sim card in there phone and selecting ?copy all to phone?. What makes this unnerving is that if you do not catch them in the act there is no way of knowing your information has been stolen.
Tip 1: Copy all of your contacts to both the phone and Sim card.
Tip 2: Lock your phone and/or Sim card.