Unlocking is the removal of SIM restrictions on the modem, allowing the use of the iPhone on any carrier. The main reason to unlock your iPhone is if you want to use it with a different service provider (ie T-Mobile). Here are 2 articles you may want to look at:

* What is unlocking an iPhone?
* The difference between jailbreaking and unlocking

This page is a reference guide for anyone looking to unlock the iPhone. Simply look for your firmware version and your iPhone model, then click on the appropriate tutorial.

Unlock Iphone IOS 4.2

* Unlock iPhone 4 iOS 4.2.1 (Coming Soon)
* Unlock iPhone 3GS iOS 4.2.1
* Unlock iPhone 3G iOS 4.2.1

Unlock iPhone iOS 4.1

* Unlock New Baseband
* Unlock iPhone 4 iOS 4.1(Old Baseband)
* Unlock iPhone 3GS iOS 4.1(Old Baseband)
* Unlock iPhone 3G iOS 4.1(Old Baseband)

Unlock iPhone iOS 4.0.2

* Unlock iPhone 4 4.0.2 With UltraSn0w
* Unlock iPhone 3GS 4.0.2 With UltraSn0w
* Unlock iPhone 3G 4.0.2 With UltraSn0w

Unlock iPhone iOS 4.0.1

* iPhone 4 unlock with UltraSn0w
* iPhone 3GS unlock with UltraSn0w
* iPhone 3G unlock with UltraSn0w

Unlock iPhone iOS 4

* Unlock iPhone 3GS iOS 4 with RedSn0w
* Unlock iPhone 3G iOS 4 with RedSn0w

Unlock iPhone 3.1.3

* Unlock iPhone 3GS 3.1.3 with UltraSn0w
* Unlock iPhone 3GS 3.1.3 baseband 05.11.07 with BlackSn0w
* Unlock iPhone 3G 3.1.3 with UltraSn0w
* Unlock iPhone 3G 3.1.3 baseband 05.11.07 with BlackSn0w
* Unlock iPhone 2G 3.1.3 with RedSn0w

Unlock iPhone 3.1.2

* How to unlock iPhone 3GS 3.1.2
* Unlock iPhone 3GS 3.1.2 with BlackSn0w tutorial
* How to unlock iPhone 3G 3.1.2
* Unlock iPhone 3G 3.1.2 with BlackSn0w tutorial
* Unlock iPhone 2G 3.1.2 with PwnageTool

Unlock iPhone 3.1

* iPhone 3GS 3.1 unlock with UltraSn0w
* iPhone 3G 3.1 unlock with UltraSn0w
* iPhone 2G 3.1 unlock with PwnageTool for Mac OS X

Unlocking iPhone 3.0.1

* Unlock iPhone 3GS 3.0.1 with UltraSn0w
* Unlock iPhone 3G 3.0.1 with UltraSn0w
* RedSn0w iPhone 2G 3.0.1 unlocking tutorial for Windows and Mac

Unlocking iPhone 3.0

* Unlock iPhone 3GS 3.0 using UltraSn0w (recommended)
* PurpleSn0w unlock for iPhone 3GS 3.0
* Unlock your iPhone 3GS 3.0 using PurpleRa1n and UltraSn0w
* Unlocking the iPhone 3G 3.0 with UltraSn0w
* PwnageTool unlock tutorial for iPhone 2G 3.0 on Mac
* RedSn0w unlocking tutorial for iPhone 2G 3.0 on Windows and Mac