You've probably heard the term "unlocked phone" floating around, but you may not know precisely what that means. An unlocked cell phone is one that's not tied to a specific carrier or long-term contract; in fact you can use it on multiple carriers at home and abroad, making it a flexible travel companion. You can buy an unlocked phone at retail or, with some exceptions, unlock a cell phone that you've purchased through a carrier; there are pros and cons to unlocking a phone. It really comes down to how you plan to use your cell phone; not everyone will benefit from an unlocked phone. And it's important to remember that even an unlocked phone has restrictions.
When a phone is "locked," it means essentially that it's tied to one carrier, which is the case with most cell phones purchased in the U.S. For example, if you buy a phone through Verizon, and then switch to Sprint or AT&T, you'll have to buy a new phone. Verizon Wireless and Sprint use the CDMA (Code Division Multiple Access) network, and currently CDMA phones cannot be unlocked. If you want an unlocked phone in the U.S., it has to be a GSM (Global System for Mobile) phone, so your choice of carriers is limited to AT&T and T-Mobile. See our report on cell phone plans for more information.
You can buy a phone that's already unlocked, though you still have to get it activated by a carrier in order to get service, but you don't need to sign a contract and can cancel service at any time. Unlocked phones are generally on the expensive side because the carrier doesn't subsidize the cost. The upside to buying an already unlocked phone is that it should work equally as well with any carrier that sells SIM cards. You can find unlocked phones at a number of online retailers including Cellhut.com, Dynamism.com and even Amazon.com.
The benefit of buying a locked phone through a carrier, is that carriers will subsidize the price of the handset as long as you sign on to a one or two year contract; that's how you're able to get many phones for free or under $50. Typically, when you renew your contract, you'll get money toward a new phone, depending on the carrier. While phones that you buy through a carrier are locked by default, there are ways to unlock GSM phones; we cover that in the next section.
The reason that GSM phones can be unlocked is because they use a removable Subscriber Identification Module (SIM) card to store all of your data, including your phone number. A SIM card is about the same size and shape as a microSD card and is often located underneath the battery. With an unlocked phone, the SIM card can be swapped out and replaced with a card from a different carrier or transferred to a new handset. The CDMA standard that Verizon and Sprint use actually has a counterpart, called the R-UIM (removable user information module), but U.S. carriers have chosen not to implement it.
Verizon Wireless and Sprint sell CDMA/GSM hybrid phones that work on the CDMA network in the U.S. and some GSM networks abroad, including Europe, but these phones are not unlocked. None of these phones will work on the U.S. GSM network. Cell phones and smartphones are designed to work on specific frequencies, or bands; some of these phones are described as tri-band or quad-band. The U.S. GSM network is on the 850 MHz and 1900 MHz band, while most other countries have GSM networks on 900 MHz or 1800 MHz.
Verizon models, which include the BlackBerry Storm (*Est. $100 with new contract), BlackBerry 8830 (*Est. $100 with new contract) and the Samsung Saga (*Est. $200 with new contract), have removable SIM cards, but you'll have to contact Verizon in order to use a different SIM card abroad. According to PCMag.com, after 60 days, Verizon will unlock the SIM card slot to let you use any SIM you want. Sprint has its own version of the BlackBerry 8830 (*Est. $170 with new contract); other world phones include the Samsung Ace (*Est. $200 with new contract) and a handful of Nokia models. Sprint's phones are automatically unlocked for international use, so you can swap in international SIM cards when you travel.
So what if you want to switch carriers, but keep the same phone? It's as simple as swapping out the SIM card; well, almost that simple. It's important to note that just because your phone has a removable SIM card, it doesn't necessarily mean your phone is unlocked. In the U.S., carriers lock GSM phones by programming them to work only with their SIM cards. For instance, the Apple iPhone has a removable SIM card but if you try to use a different SIM card, say from T-Mobile, it will not work. Most GSM phones can be unlocked, though, and it can be as simple as entering an "unlock code," which you'll have to get from the carrier. T-Mobile will unlock your phone if you have an active account in good standing for at least 90 days. The only exception is T-Mobile Sidekick phones, which cannot be unlocked. AT&T will also unlock your phone after 90 days, or once your contract is finished. Your first step should be to contact your service provider and ask for an unlocking code; if the carrier balks, though, there are a number of alternatives.
The easiest way is to use a third party service that will unlock your phone for a small fee. For about $5, Unlock123.com will unlock most Nokia phones. TheTravelInsider.com sells unlocking codes (*Est. $5) for most Nokia phones, and can unlock some models from Samsung, Siemens, Motorola and LG, but you'll have to send them in. That's because some models need firmware updates in order to be unlocked; and sometimes it's necessary to open up the cell phone's case. You can buy equipment and do this yourself, but it can be expensive, and most experts recommend leaving it to the professionals. It's important to note that phones that have been unlocked by a carrier don't always work properly with other carriers and may not support all of another carrier's features.
Most European, African and Asian cell phones work on GSM networks, so having an unlocked phone while traveling can come in handy. U.S. and European GSM phones work on a different frequencies, or bands, so you'll need a phone that works on multiple frequencies, otherwise known as a tri- or quad-band phone. As mentioned earlier, Verizon Wireless and Sprint sell a few world phones that work on the US CDMA network and GSM networks abroad, including Europe (but not the U.S. GSM network).
If you travel frequently, it might be worthwhile to purchase an unlocked phone and buy SIM cards for the countries you visit often. You can buy a SIM card once you arrive at your destination or buy it online ahead of time. Many experts recommend Telestial.com, a store that sells prepaid SIM cards for most countries; it also offers cell phone rentals. If you run out of airtime while abroad, you can add minutes at local cell phone shops. In Europe and many countries outside the U.S. prepaid service is more popular than contract service, so finding a store that will replenish your card shouldn't be difficult. Telestial.com also sells unlocked cell phones, many of which offer basic features and sell for under $100.
Looking for a cell phone? We've got reviews of more than 200 cell phones and smartphones.