Will Your Mobile Phone Work in Asia?

Two of the most common travel tech questions when traveling to Asia include:

• Will my cell phone work in Asia?
• What's the difference between GSM and Asian cell phones?

Despite the road being notoriously tough on delicate devices, there's realistically little chance that you'll be leaving the smartphone behind. Even if not used for calls, it's a quick way to take photos and check in with loved ones back home.

But will that smartphone work in Asia? Should you risk a $700 flagship phone or simply purchase a cheap Asian cell phone to use for the duration of your trip?

Using a Smartphone in Asia

While much of the world goes one direction, the U.S. often chooses a different path. The U.S. has a long history of balking international technology trends and standards: Electricity, DVDs, telephones, and use of the Metric system are just a few examples. The cell network in the U.S. is no different, so not all American mobile phones will work abroad.

In a nutshell, these requirements must be met to use a cell phone in Asia:

• The phone must be the correct hardware standard (GSM or CDMA) for the country you are visiting.
• Your phone must be multi-band or operate on the correct frequency.
• Your phone must have international roaming capability or be unlocked to work with foreign SIM cards and networks.

The most reliable way to find out if your mobile phone will work in Asia? Call the carrier and ask. While you've got them on the phone, you can find out about getting your smartphone "unlocked" to work on other networks, if it isn't already.

Although common before, it's no longer necessary to pay someone to unlock your smartphone! In 2014, the Unlocking Consumer Choice and Wireless Competition Act went into effect requiring mobile phone carriers to unlock your phone for free once it's paid off, and your contract has been fulfilled. With an unlocked GSM phone, you can get a SIM card and join networks in Asia.

Tip: Don't let your carrier talk you into purchasing or renting a SIM card for your destination country. You'll be able to get one much cheaper once you arrive in Asia.

CDMA vs. GSM Phones

Most of the world uses the Global System for Mobile Communications standard, better known as GSM. Europe mandated the standard in 1987 after a consortium, and most countries adopted it. The most notable exceptions are the U.S., South Korea, and Japan — all of which use the CDMA standard. CDMA is based on a proprietary standard mostly created by Qualcomm, an American semiconductor company.

Having a phone that works on the correct standard is only half of the equation. American CDMA cell phones operate on the 850 MHz and 1900 MHz frequency bands, while South Korean and Japanese phones use the 2100 MHz band. Your cell phone will have to be tri-band or quad-band to work abroad — check the phone's hardware specs.

The Best Mobile Phone Carrier for Travel

The most popular carriers in the U.S. that are compatible with the GSM network are T-Mobile and AT&T. Customers with Sprint, Verizon Wireless, and other CDMA carriers typically aren't able to join the local cell networks in much of Asia aside.

T-Mobile is a popular choice for travelers in Asia because they offer free data roaming (allowing you to surf the web and make internet calls) without changing hardware. You will have to contact them to ensure that international data roaming is activated on your plan. Choosing this strategy means that you'll have to rely on Skype, WhatsApp, or other internet calling (VoIP) apps to make calls or risk being charged very expensive voice roaming fees.

International Roaming

If your cell phone meets the hardware requirements, you'll have to decide between international roaming — which can get very expensive — or unlocking it to use a SIM card with a local number and prepaid service.

International roaming allows you to keep your number from home, however, you'll pay each time that someone calls you or vice versa.

Tip: When using a prepaid service in Asia, deactivate data roaming on your smartphone to avoid big, unexpected charges due to apps updating in the background. Applications quietly checking the weather or updating news feeds can eat up your credit!

Unlocking a Cell Phone

Your phone must be unlocked to work with SIM cards on other networks. Your mobile provider should do this for free if your phone is paid off and you are in good standing. In a pinch, cell phone shops around Asia will unlock your phone for a small fee.

You will need to provide the IMEI number of your phone to tech support; the number can be found in many places. Check the original packaging for a sticker, the "About" settings, or beneath the battery. You can also try dialing *#06# to retrieve the IMEI.

Store the unique IMEI number somewhere secure (e.g., in an email to yourself). If your phone is ever stolen, many providers will blacklist your phone so that it cannot be used, and a few may even be able to track it.

You should only have to unlock your cell phone once for international travel.

Purchasing a local SIM card

A SIM card provides you with a local number for the country you are visiting. Carefully replace your current SIM card with the new one by turning off your phone and removing the battery. Keep your old SIM card somewhere safe — they are fragile! New SIM cards need to be activated to join the local network; methods vary, so refer to the instructions included or ask the shop for help.

SIM cards contain your local phone number, settings, and even store new contacts. They are interchangeable and can be moved to other Asia cell phones should you swap or purchase a new one. Your SIM card will expire after a certain number of weeks or months to put the number back into the pool. Purchasing credit regularly will prevent the card from expiring.

SIM cards with credit can be purchased in shops, 7-Eleven minimarts, and in cell phone stores around Asia. The easiest time and place to get your smartphone read for Asia is to approach one of the many cell phone kiosks or counters after first arriving at the airport.

Adding Credit

Known throughout Asia as "top up," your new SIM card may come with a small amount of credit or none at all. Unlike monthly cell phone plans in the U.S., you'll need to purchase prepaid credit to make calls and send texts with your phone.

You can purchase top-up cards at minimarts, ATM-style kiosks, and in shops. Top-up slips come with a number that you enter into your phone. You can check the remaining balance on your phone by entering a special code.

Other Ways to Call Home

Travelers on shorter trips can avoid the entire ordeal of getting onto the local cell network simply by just taking advantage of free Wi-Fi to make VoIP calls using software such as Skype, Google Voice, Viber, or WhatsApp. You can call other users for free or dial landlines and mobile phones for a small fee.

Although clearly, the cheapest and easiest way to avoid getting an Asian cell phone, relying on internet calling means that you won't have a local phone number to give to new friends, businesses, etc.

Wi-Fi is widespread throughout Asia. South Korea was even declared the most connected country in the world and enjoys more internet bandwidth than anywhere else. You won't have any problems finding Wi-Fi in cities and tourist areas.

In a pinch, there are still plenty of internet cafes in Asia if you don't mind making a call over the sounds of World of Warcraft.