How to Unlock Your iPhone

 If you're one of the million people who've purchased an iPhone since the end of June, you probably signed up with Apple's exclusive carrier in the U.S., AT&T, when you activated your phone. That means your iPhone identifies itself to AT&T's network using an AT&T SIM card, a smart card that's located in a small tray between your iPhone's sleep/wake button and its recessed headphone jack.

 But what if you're planning a trip to Europe and rather than paying AT&T to use the networks of its European partners, you want to take advantage of the favorable rates and local phone numbers offered by replacing your AT&T SIM card with a pre-paid European card? Or what if you'd prefer to use T-Mobile as your cellular provider, rather than AT&T?

In the past month several groups have announced that they've found a way to "unlock" the iPhone, allowing it to use a SIM card from any provider. (Keep in mind that this is only half the story: the iPhone uses the GSM radio band for its communications, meaning that it'll only work with providers that use the GSM network. In the U.S., that means T-Mobile and AT&T.)

In August, a group of hackers demonstrated a method for unlocking SIM cards and sold its software to resellers, who in turn began selling it to the public for as much as $100 last week.

But another group has came up with its own hack that, with the help of some free, open-source software, lets you unlock your iPhone in about an hour, free of charge. Below, I'll show you how it works - and it does work, because I've used this technique to unlock my own phone. (One important caveat: Certain AT&T-only features, such as Visual Voicemail, will not work when you're connected to other cellular networks.)

Before we get started, you'll want to disable the iTunes helper application that may get in the way of the installation. Make sure iTunes is not running, then open OS X's Activity Monitor in the Utilities folder of the Applications folder. Search for or scroll down to iTunes Helper, select it, and then click on the Quit Process button in the top left of the screen. You'll also need your iPhone, your data cable, and a Wi-Fi connection to the Internet.

(If you haven't already activated your iPhone with AT&T-and aren't planning to-you need to conduct a fake activation. To do this, you'll need to follow the excellent instructions at ModMyiPhone and download and install a program called iNdependence.)

Install AppTapp

Apple doesn't support the installation of third-party applications on the iPhone, but the enterprising developers at NullRiver have created a program called AppTapp that will let you install including chat clients, games, and other pieces of software - including those that are needed to unlock your iPhone.

Apple iPhone 4 Review

Editor's Note: With the release of the iPhone 4S the iPhone 4 is no longer Apple's flagship smartphone. Nevertheless, it's still a powerful device and one that's available at a very good price: $100 with a two-year servuce contract.

  It's also received a number of system software updates since this review was first written, and is now running iOS 5.0. This means it has most of the features of the iPhone 4S except the Siri voice-recognition system. 

Every year Apple hits us with a new, shiny iPhone. This year, we are finally getting features that we've wanted for a while now, such as a new design, front facing camera, a better quality camera with flash, and of course a much improved screen.

The iPhone 4 also packs some hidden treats on the inside, making this the best model so far. Is it worth the upgrade from the iPhone 3G? Did you just recently buy an iPhone 3GS and you aren't sure if you want to upgrade already? Or maybe you have never owned an iPhone yet and are thinking the iPhone 4 might be the time to switch. Keep reading to find out, and see if the iPhone 4 can live up to your expectations.

Note: Pay attention to all the pictures in this review, as they were taken strictly with the new iPhone 4 camera.

DESIGN & BUILD

Apple gave the iPhone 4 a design overhaul from the previous 3GS version. The new model is only 0.37 inches thin, compared to its predecessor which is 0.48 inches.

There is no plastic on the exterior of the iPhone 4, and the standard silver bezel that was the trim to all previous iPhones is now gone. The front and back now glass. Supposedly, the glass used is "30 times harder than plastic", and is "comparable to the strength of sapphire crystal", according to Apple's Jonathon Ives.

Between the two pieces of glass is an aluminum strip that wraps around the entire phone. The cool part about this is that the metal trim serves as an antenna for 3G, Wi-Fi, GPS, and Bluetooth, which helps signal significantly.

Display

When you first look at the display on the iPhone 4, it is simply gorgeous. This is without a doubt one of the best improvements on the new model. The new screen resolution is 960 x 640, up from 480 x 320 on all previous iPhones and iPod touches.

Since the screen didn't get any bigger, there is a lot more pixels per inch now -- 326 to be exact. Currently, there is no other smartphone on the market with a screen of this resolution. To the human eye, it is almost like a digital print. You really can't see any individual pixels anymore, and everything is more crisp.

 It will only be a matter of time before all the current applications are updated to support the resolution. The developers have to do little work to make this change.

Now if Apple increased the screen size of the iPhone, that would have been a completely different story, but I can't see that happening anytime soon.

Buttons and Controls

On the front of the Apple iPhone 4 you have the standard "Home" button, along with the proximity and ambient light sensor, and the biggest change, a VGA front-facing camera.

Around the outside of the device you can find the standby button, the new microSIM slot (which has some improved benefits over the standard SIM card), a speaker, a microphone, another microphone (that helps remove background noise), a headphone jack, a silent toggle, and two separate volume buttons.