An iPhone SIM card is provided by any GSM carrier. There are two competing cell phone networks world wide. GSM (Global System of Mobile Communication) and CDMA (Code Division Multiple Access).
One of the advantages of the
and iPhone 4 is that it uses GSM which has been the wireless standard globally. It uses a SIM (Subscriber Identity Module) card.
GSM is the global standard and is used by 80% of the global mobile market. This allows you to use your
in most countries in the world with some additional roaming charges of course. However, when your buy an unlocked iPhone, you can simply insert any SIM card from any local carrier and connect to it easily.
CDMA on the other hand is only available in the US and some parts of Asia. There is no SIM card in a
CDMA cell phone. Apple introduced the first CDMA iPhone that worked on the Verizon network in the US in 2011. Then Apple made a world iPhone design that is global and work on both GSM and CDMA networks.
What is an iPhone SIM Card?
An iPhone SIM card is a standard size card that looks similar to an SD card.
When you subscribe to any GSM carrier, you will be provided with a SIM card that holds your cell phone information such as your phone number and can even store your contacts. In the US an iPhone data plan is required with any SIM card you get for the
When you place this SIM card in any GSM phone like the
iPhone, all your carrier data such as your phone number and contacts become immediately available to that new
You can use different GSM phones with one single SIM card that is already active by simply swapping the card from one phone to another, your service will be automatically available on the new phone.
How does a SIM card work on unlocked iPhones?
When you buy iPhone unlocked, you will be able to use it with any GSM carrier like AT&T or T-Mobile in the US. You simply insert your existing SIM card in the
SIM card port and the service will become available immediately. No contract is required.
You will be free to change your carrier however you like and at any time to any GSM carrier. You can even buy a pre-paid SIM card, use it, then through it away.
How to replace an iPhone SIM card?
It is simple to open and remove the SIM card on the
iPhone. Insert a pin in the small hole as shown in the picture below in any iPhone 2G or 3G and push gently to slide the tray open.
The iPhone 4 uses a micro sim card which is smaller than the full iPhone sim card size.
However, there are some tools that allows you to trim the the full size iPhone sim card to a micro sim card and insert it in an iPhone 4.
Then you can use a sim card converter that converts the micro sim card to a full size sim card that can be installed in any older
In the US, you can only activate the iPhone with AT&T SIM card. It is really useless to unlock an iPhone in the US if you think about it. There is only one other GSM carrier available in the US, that is T-Mobile which uses a different frequency 3G network. Therefore, an unlocked iPhone 3G will only work over the slower EDGE network in the US with T-Mobile, there is no 3G network.
Sprint and Verizon in the US on the other hand don't use SIM cards. They use CDMA technology. Apple has a new iPhone design that support Verizon network. The Verizon iPhone is a CDMA iPhone that uses the Qualcomm chip which supports both CDMA and GSM network.