The SIM card, or Subscriber Identity Module, is the "brain" of your cell phone. This little card is used by service providers to identify users on their network. It also stores almost all of the information that goes through your cell phone (text messages, call logs, phone numbers, addresses, etc.). In order to read a SIM card, you need to insert it into a cell phone. If you don't have a cell phone to use, you can read the card remotely from your computer with a SIM card reader.
Buy a SIM card reader that will suit your needs. SIM card readers come in many sizes, can do many things, and vary widely in price. The most expensive readers will simultaneously read multiple cards, and may be able to perform special functions, like restoring deleted text messages and call logs. The cheaper ones will allow you to read and edit everything that is stored on the SIM, and will only read one card at a time. The type of reader you purchase is entirely up to you, but if all you want to do is read the info currently stored on the card, one of the cheaper models will suffice.
Plug your SIM card reader into your computer. Most SIM card readers will plug into the USB port on your computer, and are about the size of a USB flash drive. Some readers are "plug-and-play," which means your computer will automatically install all the necessary drivers as soon as you plug it in. Some readers will come with a software CD that you'll have to install after you plug in your SIM card reader.
Insert your SIM card into the SIM card reader. The SIM card will only fit one way, so it's impossible to put it in wrong. If it doesn't slide right in, don't force it; simply consult the reader's owner manual.
Open your SIM card reading software on your computer. It's likely that the program automatically opened when you inserted your SIM card, but if not, open it now. Each program will look different, but they all function in similar ways. You'll be able to search, edit, add, and delete phone book entries; back up multiple SIM cards to one location; manage SIM card codes; recover deleted or corrupted info; and export or import address books, as well as other things.