Jason Cipriani/CNN Underscored

Smartphones are a huge help when traveling abroad. From maps to guide you around a new city to entertainment on long flights, your smartphone can make your trip easier and more enjoyable. But what about your phone bill?

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Roaming with many US cell phone plans means high roaming costs. Sometimes carriers charge these based on how many texts you send, minutes you talk on the phone or how much data you use. Others charge a set daily fee, while some will include free low-speed data unless you pay up.

Thankfully, there’s a cheaper way to avoid high roaming charges if you have a relatively new iPhone or Android device that’s not locked by your carrier: eSIMs. These let you buy a prepaid data plan on a local network without having to buy a physical SIM card at a phone shop. Just download the eSIM, activate it and enjoy high-speed data.

This is often cheaper than buying international data from your US phone carrier. But where do you buy eSIMs without heading to a phone shop when you land? Let’s take a closer look at your options.

Does my phone support eSIMs?

Most modern smartphones support eSIMs if they’re not carrier locked. Henry T. Casey/CNN Underscored

Before you purchase an eSIM, ensure your phone supports them. Most newer iPhones (specifically, iPhone XS and newer), Samsung Galaxy and Google Pixel devices support eSIMs, as well as newer devices from other manufacturers.

That said, your phone cannot be factory-locked if you want to use an eSIM from one of these services. This is common if you have a payment plan for your phone through one of the major carriers. If you purchased your device outright, however, it should be compatible.

Of course, there are a few exceptions to this rule. iPhones purchased in mainland China or in Hong Kong and Macao are also not usually compatible with eSIM services, either. Check with your phone’s manufacturer and the eSIM provider to ensure your device is compatible before purchasing.

Also, note that many phones will let you keep your local phone number active while you use one of these eSIM services. For example, on most iPhones, you can have your home phone carrier active for talk and text while the eSIM provides mobile data.

Installing an eSIM is pretty straightforward. Many eSIM marketplaces have an app that will walk you through the installation process. You can also buy eSIMs online with many of these services and simply scan a QR code to add it to your device.