A Comprehensive Guide to International Data Roaming

A typical scenario: You just landed in another country. You are excited, and turn on your phone. Then, you frantically hurry to put your phone in airplane mode and turn off all data since you don’t want a huge roaming bill. It doesn’t have to be this way.  You don’t have to lose mobile data on your phone just because you’re in another country. In fact, when you arrive at a new country, that’s when you need the internet on your phone most!

One of the most common questions I get from people for international travel is how to get internet and data on their phones. This post will discuss all the major options you have when traveling using mobile data. All options are good ways you can get data on your phone and each one has their pros and cons. I will discuss all of the pros and cons for each option thus recommend which option works better depending on your travel situation. The post will also explain what “unlocked” phones are and the process on how to get your phone unlocked.

The following four options will be discussed below including the pros, cons, and recommendations for each.

Option 1 – Obtain a Local SIM card at the destination country
Option 2 – International Data Roaming with Verizon, AT&T, Sprint, and T-Mobile
Option 3 – Free international data roaming with T-Mobile and Sprint
Option 4 – Google Project Fi

Option 1 – Obtain a SIM Card at the destination country

Pros – Typically this is the cheapest option that gives the most data. Most SIM card and 1 GB of data cost no more than $20 – $30 USD, sometimes even cheaper.
Cons – Requires an unlocked phone. Activation of the SIM card can be confusing as it may be in a different language. Data will most likely only work at that specific country, so if you are country-hopping, you may have to get multiple SIM cards.
Recommended for: Longer trips; when you need a lot of data; or when you stay in one country for long periods of time

This option is to buy a local SIM card once you arrive at the destination country.  Most airports will have a few stores or counters that will sell SIM cards to use in the country. These stores are often located at the arrival area once you exit from baggage claim. At times, convenience stores around the country may sell them also.  Most SIM card and 1 GB of data should cost no more than $20 – $30 USD. These SIM cards will also allow you to make local calls in case you need to contact your hotel or someone in the country.

Before traveling, you can read up to see what people say about buying SIM cards at the airport you arrive at. For example, if you are flying to Paris into Charles de Gaulle airport, search for something like “SIM Card at Charles de Gaulle airport” or “SIM card at CDG airport”. If the airport has a lengthy or weird name, it might be best to search using the airport code. You can find the airport code on your flight itinerary.

Requirements for using an international SIM Card

For this to work, you will need an unlocked phone that works with GSM network. In the USA, if you buy a phone from a carrier such as AT&T, Sprint, Verizon, T-Mobile, etc, that phone is typically locked and will only work on their specific network. You cannot put in another SIM card and expect it to work. If you are not in a contract with the carrier and has fully paid off the phone, you can call in and ask them to unlock your phone. They should be able to unlock it for free if you fully own the phone. Use the “Chat” function at your carrier’s website and ask them.

How do you know if your phone is currently locked or unlocked? Unless you bought the phone that specifically say “unlocked” from a vendor, then your phone is most likely locked. You can call your carrier and ask them to look up whether your phone is locked or not. If your phone is locked, there are ways to unlock your phone. Read the link below and see methods to unlock your phone. You can do it for free with the carrier if it meets certain requirements, or you can use a third party company (costs ~$20 per phone)

Link – Methods to unlock your phone

The second requirement is that your phone must be compatible with GSM network and utilize a SIM card slot. All phones that work with AT&T and T-Mobile support GSM network and has a SIM card slot. Verizon and Sprint uses CDMA network, which is not compatible with the majority of cell phone service providers around the world. Plus, many Verizon and Sprint phones do NOT use SIM cards, and there is no slot for the SIM card. If your phone doesn’t have a SIM card slot, you cannot use an international SIM card. However, there are some Verizon/Sprint phones that are compatible with GSM network and can use SIM card. The biggest example is the iPhone 5. Verizon calls them “World Devices” and you can see which phone is compatible with GSM network using the links below. If you are not sure, CHAT with Verizon/Sprint representative and ask them!

Verizon iPhone 5 shown with SIM card

Link – Verizon – World Devices

Link – Sprint – Global Roaming

Lastly, you should know what type of SIM card your phone uses. The most common types today are Nano and Micro SIM cards. When you buy the SIM card in another country, the vendor will ask you for the size. Only the correct type will fit in your phone. iPhones 5 and 6 use Nano SIM cards, while Samsung Galaxy S5 uses Micro SIM cards.  You can check your phone on this list to see what it uses:

Link – Check your phone SIM card size here

If you buy a local SIM card, make sure you ask the vendor to help you activate the service on your phone to ensure that everything works. This is VERY important. Activating a new SIM card usually require you to dial the local number and press certain keys when prompted. The difficult part is the prompts are typically in the local language so you may not understand it.  Therefore, make sure the vendor helps you activate it before you leave, and test out to make sure data and everything work.

Buying a local SIM card is a good option if you plan to stay in the same country for long periods of time or if you need a lot of data. If you are country-hopping, be aware that the SIM card most likely won’t work in another country. The exception is for countries within Europe, look for a provider that will operate throughout Europe in multiple countries, such as Lycamobile. When in Europe, ask the vendor to see what countries will work with that SIM card before purchasing it.

Option 2 – International Roaming Plans with your Carriers (Verizon/AT&T/Sprint/T-Mobile)

Pros – Convenience, mobile data works once you arrive, no need for activation; data works in multiple countries; does not require unlocked phone.
Cons – Low data allowance (typically 120 MB for $30).
Recommended for – Multiple country-hopping, light data usage such as Google Maps and quick searches.

All the major carriers offer some type of international roaming plans that allow you to use your phone in any country with their roaming agreements. With this option, when you turn on your phone at that country, data will automatically work.  You do not have to waste time looking for a SIM card and activate it. This is the most convenient option for most and will work in multiple countries. The only downside is the low amount of data allowance and mainly useful for limited data usage. These roaming plans must be activated before you go on your trip. You can do this by logging into your account online and adding the respective “package”. This package will be active on the date of your choosing and will last the number of days designated by your carriers (usually 14 or 30 days). Make sure you do this prior to the trip, otherwise data roaming without a plan activated is very expensive.

Here is summary of the major carriers and what they offer. See additional plan details at each of the link. Note the prices and data allowance is for international countries EXCEPT for Mexico/Canada. For travel to Mexico/Canada, check out the links below for specific prices and options. Some carriers provide cheaper or free data to Canada/Mexico and has specific packages for those two countries.

International Roaming Packages from US Carriers

  • AT&T 
    • 3G data for $30, includes 120 MB for 30 days
    • $60 for 300 MB, $120 for 800 MB
  • Verizon
    • 3G data for $25, includes 100 MB for 30 days
    • $50 for 250 MB
  • Sprint
    • Free unlimited 2G data (slow)
    • Faster 3G data available for $25, includes 200 MB for 7 Days
    • Number of countries with coverage is much less than AT&T/T-Mobile, check the coverage map
  • T-Mobile
    • Free unlimited 2G data (slow) to 140+ countries
    • Faster 3G data available for a fee ($50 for 500 MB for 14 days)
    • Best in terms of free data for the most number of countries

As you can see, T-Mobile and Sprint actually provide free 2G data to many international countries where they have service agreements with. Sprint world coverage is a lot less than T-Mobile though. T-Mobile currently offers the best plan of free 2G data to over 140 countries. However, 2G data is slow but will work for Google Maps usage and light web browsing. It’s good when you need to look up something while on travel.

I have used the international roaming plan with AT&T many times and it works well. Data works right away once you land in the country and continue to work even if you hop to different countries in one trip. I found myself using this option more than getting SIM cards because it’s just easier. However, the data allowance is not much so I mostly use it for Google Maps and navigating purposes.  If you go over the MB allowance, they will typically charge you the same ~$30 for another 100 or 120 MB of data.

Option 3 – Carriers that provide FREE international roaming (T-Mobile and Sprint)

Pros – It’s FREE. No need to buy any SIM card or activation. No need for unlocked phone.
Cons – Free data is limited to 2G speed, which is slow.
Recommended for – Convience, no need to buy any roaming plans or SIM cards. 2G data is good for Google Maps and light browsing to look up restaurants, etc.

Most T-Mobile plans provide free 2G data for 140+ countries in the world. 2G data is slow but can be used with Google Maps and other light browsing activities. This is a good option if you just need data for navigating around the city and simple web searches for restaurants and landmarks. Best of all, it’s FREE. See Option 2 above for more information.

Sprint now offers free 2G data too but their coverage map is much more limited than T-Mobile. Check their website and see what country has coverage under Sprint.

Option 4 – Google Project Fi

Pros – Cheap data to many countries around the world
Cons – No joint or family plans. Data cost can be high if you use a lot of data within the US.
Recommended for – Frequent international travelers

Project Fi is a new service plan offered by Google. The price is basically $20 for the base rate which includes unlimited talk and text, and $10 for each 1 GB of data. I will write a full review of this service in a future post. What’s most important is Project Fi data can be used around the world. The cost is the same $10 for 1 GB of 3G data anywhere in the world that has coverage.

Project Fi does not actually have their own network.  Rather, it uses Sprint and T-Mobile networks. So for international roaming, it mainly uses T-Mobile’s network. Basically, you don’t pay anything extra for data even when roaming, it costs the same as if you were to use data in the USA. However, data when roaming is limited to 3G speeds, rather than 4G LTE that is available in the US. In essence, you are getting 3G data at the cost of $10 per 1 GB. This is definitely a lot cheaper than any international roaming plans currently offered by any US carrier.

The network they use is the same as T-Mobile. The major difference between Project Fi and the free T-Mobile data is the speed offered. T-Mobile 2G roaming is free and 3G is available for $50 for 500 MB. Project Fi gives you the same 3G speeds for only $10 per 1 GB (1000 MB).

My actual Project Fi monthly bill statements

So if you’re a frequent international traveler, Project Fi is a good option you can consider as the price is the lowest for the most data plan. The drawback is Project Fi only works on a limited number of phones and does not offer any type of family or joint plans. Another drawback Project Fi uses T-Mobile/Sprint network within the US. Both of these networks combined does not have as much coverage as either Verizon or AT&T.

I am currently using Project Fi and it has worked well so far.  I will write a full review in the near future. Project Fi is not good for travel within the US, especially to places outside major cities or remote locations, as the coverage is extremely limited. In order to compensate this, Tam has AT&T in order to get coverage in areas where Project Fi does not.


In conclusion, any one of these options could satisfy your need for mobile data when traveling. Each option has its own pros and cons, and none is really superior to the other. It really depends on your travel situation to determine what is the best option. I hope you find it useful, and if you have any questions feel free to leave a comment and I’ll be glad to answer it.

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