How to Unlock Your Cell Phones

Unlocking your mobile phone gives you more freedom and flexibility, letting you use the device on other wireless carriers. Here's what you need to know about unlocking your phone and how to go about it.

What Does It Mean to Unlock Your Phone?

Typically, cell phones are tied to just one service provider, so you can't use it on a different one unless you buy an unlocked phone or unlock it. For example, if you decide to switch from AT&T to T-Mobile, you normally can't use the same phone unless the phone is unlocked. Also, you usually can't take your phone overseas and hope to use it on a different network there without unlocking your phone first or making arrangements with either your home carrier or the foreign one.
In short, unlocking your phone allows you to use your phone on more carriers.

Why you might want to unlock your phone: 

Besides being able to use your phone on a wireless carrier, you can sometimes use an unlocked phone not available on your current carrier if it's unlocked (for example, back when T-Mobile didn't carry the iPhone, some users bought unlocked iPhones that worked with Mobile. This, however, depends on the phones and carriers being compatible. AT&T and T-Mobile run on GSM technology which is the most popular network type.while Verizon and Sprint are CDMA.)

Additionally, you might want to unlick your phone if you're planning on selling it--which could net a higher price and make the phone more attractive to more potential buyers. If your phone is unlocked and you travel to an international destination, you could avoid crazy data roaming fees buy renting a local prepaid SIM card and using it in your unlocked phone.

Reasons not to unlock your phone: 

Besides the small hassle of unlocking your phone, the biggest reason not to do this used to be legal: In 2013 until recently 2014, cell phone unlocking without your carrier's permission was illegal because of the terms of Digital Millennium Copyright Act. Though I'm not sure how many people were actually legally prosecuted for this.
The new bill that makes cell phone unlocking legal thanks in large part to a petition on We the People might not, however, be permanent. It just provides an exemption for another year to 2015. We'll face this issue again when the Library of Congress, responsible for considering DMCA law, reviews it next year.

Otherwise, like jail breaking and rooting, unlocking your phone gives you more freedom and flexibility especially if you travel a lot.

How to Unlock Your Phone:

To be clear, rooting or jailbreaking won't unlock a phone you need a separate procedure. To unlock your phone, you can ask your carrier to do it (many computer and cell phone repair places offer this service). GSM phones, which have removable small cards called SIM cards, are easier to unlock; again, AT&T and T-Mobile are the two GSM providers in North America. Other methods include using special unlocking software or buying an unlock code (search your phone model plus "unlock" to find them), but some software methods require your phone to be jailbroken before you can use the unlocking software.

You'll also find unlocked phones for sale on Amazon and elsewhere, but the cheapest and easiest route will probably be to just head to your carrier and ask. Here are the unlocking polices for Verizon, AT&T, T-Mobile, and Sprint.