Cell Phones & SIM Cards: What You Need to Know as a Traveler

Cell Phones & SIM Cards: What You Need to Know as a Traveler

When you go abroad, you won’t be able to continue using your smartphone as-is; there are a few important steps you’ll have to take to make sure you’re fully connected during your Greenheart Travel experience.

What is a SIM card?

Your smartphone has two ways of connecting: Wi-Fi and cellular data. Wi-Fi works only when you’re near a router and know the password. This works the same no matter where you are in the world – like your laptop, you could connect your phone to the Wi-Fi at your new home in Thailand or Spain or Australia and it will access the internet the same as it would back home.

Cellular data is what you pay your cell phone company for. Your plan probably includes unlimited calls and texts, and anywhere from 5GB to unlimited data, all of which work even when you have no Wi-Fi. When you’re outside of Wi-Fi range, this is where all your connection comes from. Think of this as everything you lose when you go into Airplane Mode – non-Wi-Fi internet, calls, and SMS (text messages).

Your SIM card, a little removable chip inside your phone, is what makes those cellular data services possible. When you pay your phone company for calls, text, and data, they tell your SIM card to make that happen. If you stopped paying your phone bill, they’d turn this off and you’d be limited to just Wi-Fi use. Same deal if you physically take your SIM card out of your phone – your phone would basically function like your laptop and work only on Wi-Fi, with no calls or texts getting through.

Why can’t I just take my phone abroad and keep using it like normal?

Depending on your provider, you might be able to. However, this would mean you still have a US number, which will make it difficult for people in your destination country to contact you. It will also probably cost a lot – cell phone companies charge huge fees for international use. Depending on where you are and what provider you have back home, your cell service might not even work while you’re abroad. It’s much cheaper and easier to use a phone company based in your destination country.

If you’re worried about losing your phone number, or you’re only going abroad for a few months, most providers will pause your service. This way, you’ll keep your number and not have to break your contract, but you will pay about $10/month instead of your full bill.

So how do I make my phone work while I’m abroad?

Most phones, especially in the US and Canada, are locked to your provider. This means that your AT&T iPhone, for example, is programmed to only work with an AT&T SIM card. If you go buy a Sprint SIM card, your phone will tell you it’s not valid, and you’d be limited to only Wi-Fi use (no calls, texts, or non-Wi-Fi internet). This means that when you go abroad, your phone won’t accept a foreign SIM card.

Therefore, it’s important to get your phone unlocked before you go abroad. This will free your phone to work with any SIM card in the world, so you’ll be able to use a local data provider in your destination country, saving you a lot of money and hassle. To do this, contact your cell phone provider before you go abroad, and they’ll give you an unlock code. When you get to your destination and buy your local SIM card (at convenience stores or cell phone stores), you’ll put it in your phone and a message will pop up asking for that code; once you enter it, your phone will start working with your new data provider.

Different providers have different rules on this. If your provider refuses to unlock your phone, you can buy an unlocked phone online, or purchase one at a phone store when you get to your destination country.

What kind of service will I have abroad?

In the US and Canada, it’s typical for cell phone plans to include calls, SMS (text messages) and data (non-Wi-Fi internet connection). However, in many other parts of the world, calls and SMS are very expensive, so most plans only include a fixed amount of data. It’s also very common that instead of getting a plan, people buy data as they go. For example, in Thailand, you can run into 7-11 and buy 5GB of data from the cashier, which is then sent directly to the Thai SIM card in your phone. You’ll have that until you use it up, then you’ll buy more – there’s no specific amount per month. This varies in price around the world but is generally much cheaper than your plan with your home provider.

Because most people don’t pay for calling and SMS services, it’s very common for people around the world to use WhatsApp, an app the runs over cell data or Wi-Fi and allows you to make calls and send text messages within the app. Download this before you go abroad! We also recommend having your friends and family back home download Wi-Fi-capable apps like WhatsApp, Skype, or Facebook messenger, to easily communicate with you while you’re abroad.


Your SIM card is a removable chip that makes your phone work when it’s not connected to Wi-Fi. They’re country-specific, so when you go abroad, you’ll need to:

  • Get your phone unlocked so that a foreign SIM will work in it (or buy a new unlocked phone)
  • Cancel or pause your home cell phone service
  • Buy a SIM card in your destination country and buy pay-as-you-go data
  • Download communication apps like WhatsApp to make local and international calls and texts

Did you find this information helpful? Let us know in the comments below.

2 thoughts on "Cell Phones & SIM Cards: What You Need to Know as a Traveler"

  1. Cathy Webber says:

    will we have the address of the homestay early I was gonna order my daughter a walking wifi so she can call me through what’s app or facebook? If not where would be place to send when I order it? She is going to Fukuoka ,Japan

    1. Allison Yates says:

      Hey Cathy! 🙂
      Students receive their host family placements roughly 2-4 weeks prior to departure. You’ll have enough time to get the pocket WiFi prior to her departure. In any case, you can always send it to the language school. So glad to hear you’re planning ahead so well!

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