Changing your SIM card allows you to use any device on your provider's network, so you can quickly change between multiple devices based on your current needs. If your SIM card goes bad, you can swap out SIM cards on your current device, although doing so may cause you to lose some information.
What is a SIM Card?
Before you can fully understand what information may be lost when changing your SIM card, it's helpful to understand just what a SIM card is. Each SIM card has a unique identification number that matches the number on your wireless account. That means that whenever you place your SIM card into a device, the network checks the number on the card so it can be sure that any activity on the device is tied to your wireless account. If your SIM card goes bad, your wireless carrier provides you with a replacement card that you can insert into your device instead of your original card.
Information Stored on SIM Card
Because people didn't want to lose their information when they moved a SIM card between one device and another, the cards were designed to store a few pieces of important information. Originally, SIM cards could only store your contact list, so that you would have access to all your stored phone numbers regardless of what device you were using. Over time, SIM cards were able to store a few pieces of additional information including text messages and even a few pictures.
Changing Your SIM Card
When you remove your SIM card from your phone and replace it with another card, you lose access to any information on the original card. This information is still stored on the old card, so any phone numbers, addresses or text messages that you lose are available if you insert the old card into the device. Information not stored on the SIM card, such as videos, applications or documents, is still available on the original device. Some devices also allow you to copy your SIM contents to the device memory, so activating this feature before swapping your SIM card means your information remains available after you make the switch.
SIM Card Copiers
If you have to change to a new SIM card but don't want to lose any of the information stored on your SIM card, you can use a SIM card copier to move information from one SIM card to another. The second SIM card loses any information it already has on it and becomes an exact copy of the first card, with the only difference being the unique identifier number, which remains different from the original card.