Ultimate Guide to Cellphone Roaming in Southeast Asia

1. Introduction

Are you simply unable to travel without your smartphone and a broadband connection? Take heart: under the right circumstances, you don’t have to leave home without your phone.

2. Can I Use My Own Phone in Southeast Asia?

So you want to use your own phone when traveling in Southeast Asia. There is a catch – several of them, in fact. You’ll be able to use your phone only if:

  • Your phone uses the GSM cellular standard;
  • Your phone can access the 900/1800 band;
  • Your phone’s SIM can access the local networks, which means that:
    • Your provider allows international roaming; or
    • Your phone is SIM-unlocked, allowing you to use prepaid SIM cards.

GSM Cellular Standard

Not all cellphone providers are created equal: in the U.S., digital cellular networks are split between GSM and CDMA. U.S. operators using the GSM standard include AT&T Mobility and T-Mobile. US Cellular, Verizon Wireless and Sprint use the incompatible CDMA network. Your CDMA-compatible phone won’t work in a GSM-compatible country.

900/1800 Band

Outside the U.S., Japan, and Korea, the world’s cellular phones use GSM technology. However, the U.S.’s GSM networks use different frequencies than the rest of the world. In the United States and Canada, GSM cellphones use the 850/1900 band; providers everywhere else use the 900/1800 band.

That means a dual-band GSM phone that works perfectly in Sacramento will be a brick in Singapore. If you have a quad-band phone, that’s another story: quad-band GSM phones work equally well on 850/1900 and 900/1800 bands. European phones use the same GSM bands as those in Southeast Asia, so no problem there, either.

3. What If My GSM Phone Is Locked?

Even if you have a GSM phone that can access the 900/1800 band, your cellphone may not always play well with local networks. Check with your carrier if your contract allows you to roam internationally, or if your phone is unlocked for the use of other carriers’ SIM cards.

The SIM (Subscriber Identity Module) card is unique to GSM phones, a transferable “smart card” that holds your phone settings and authorizes your phone to access the local network. The card can be switched from one phone to another: the phone simply assumes the new SIM card’s identity, phone number, and all.

4. Should I Roam with My Current Plan?

Does your plan allow International roaming? Check with your phone operator if you can use your phone in Southeast Asia, and what services you can use while you’re roaming. If you’re a T-Mobile user, you can read T-Mobile’s International Roaming Overview. If your phone uses AT&T’s network, you can find the info you need at their Roaming Packages page.

Be warned: it will cost you a lot more to make or receive phone calls while roaming abroad, to say nothing of using your iPhone to check into Facebook from overseas. Beware of push email and other apps tapping the Internet in the background; these can tack a few extra zeroes on your bill before you know it!

  • PROS: Use your own cellphone and get billed on the same account you use at home.
  • CONS: Expensive, limited coverage; if you’re browsing the Internet while roaming, you can rack up those data roaming fees pretty quick.

5. Should I Buy a Prepaid SIM?

If you have an unlocked quad-band GSM phone, but you think you’re being stiffed by your provider on your roaming fees, you might also consider buying a prepaid SIM card in your destination country.

Prepaid SIM cards can be bought in every Southeast Asian country with GSM cellular service: simply buy a SIM pack, insert the SIM card into your phone (assuming it’s unlocked), and you’re ready to go.

Prepaid SIM cards have a “load,” or balance, included in the package. This balance is deducted as you make calls on the new SIM; the deductions depend on the rates included with the SIM card you purchased. You can “reload” or “top up” your balance with scratch cards from the SIM card’s brand, which can usually be found at certain convenience stores or sidewalk stalls.

6. Choosing the Right Prepaid SIM

The region’s major cities and tourist spots are mostly covered by each country’s cellular providers. Southeast Asia’s mobile penetration rate ranks among the highest in the world.

Every country has a number of prepaid GSM providers to choose from, with varied bandwidths available. 4G and 4G+ connections are commonplace in digital economies like Singapore, Thailand, and Malaysia.

Even low to middle-income countries like the Philippines, Cambodia, and Vietnam possess advanced voice and mobile Internet networks concentrated around their urban centers. The closer you are to the cities, the greater your chances of getting a signal.

For details on individual prepaid cellular providers in Southeast Asia, check the respective provider’s homepage for each card’s available services, call costs, and Internet packages:

  • Brunei: DST, Progresif
  • Cambodia: Cellcard/Mobitel, CooTel, Metfone, Smart, or qb
  • Indonesia: Indosat, Telkomsel, or XL Axiata
  • Laos: Beeline, ETL, Lao Telecom, or Unitel
  • Malaysia: Celcom, U Mobile, DiGi, or Maxis
  • Myanmar: MPT, Ooredoo, Telenor
  • Philippines: Globe or Smart
  • Singapore: M1, Singtel, or Starhub
  • Thailand: TOT, True Move, AIS, or DTAC
  • Vietnam: Mobifone, Vinaphone, or Viettel Mobile

7. Getting Internet Access on Your Prepaid GSM Line

The great majority of the carriers provide Internet access, but not all providers are created equal. Access to the Internet depends on the country’s 3G/4G infrastructure.

Getting Internet access on your prepaid line is generally a two-step process:

  1. Top up your prepaid credits: Your prepaid SIM will come with a small amount of call credits, but you should top up with an additional amount to determine how much calling/texting you can do from your phone.
  2. Buy an Internet package: Use your call credits to purchase Internet packages, which usually come in blocks of megabytes. Prices depend on the number of megabytes purchased and the length of time you can use them before expiration.

Can you skip step 2? Yes, but as I learned to my distress in Indonesia, using your prepaid credits to buy Internet time is massively expensive. Step 2 is like buying megabytes at wholesale prices; it is not advisable to keep paying retail.

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