How to Activate Your eSIM (and Turn On Data Roaming)

Activating a travel eSIM is usually a two-stage process. First you install the profile (ideally before you travel, over Wi-Fi). Then, when you reach your destination, you activate it by turning on the eSIM line, selecting it as your mobile data line, and switching on data roaming for that line so it can connect to a local partner network. For most plans the clock on your data only starts once the eSIM connects to a network abroad — not when you install it.

Always check your provider’s own instructions too, since a few plans start on a fixed date or on first install. If you have not installed yet, see install on iPhone or install on Android first.

Before you fly

• Install the eSIM profile while you still have Wi-Fi at home.
• Label your lines clearly, for example Home and Travel.
• Leave data roaming OFF for both lines for now. This avoids your phone connecting early or your home line roaming at full price.
• Keep your home line as the default so nothing changes until you want it to.

On arrival: iPhone

1. Turn off Airplane Mode (or restart the phone after landing).
2. Go to Settings > Cellular (or Mobile Service).
3. Tap your travel eSIM line and make sure Turn On This Line is enabled.
4. Switch on Data Roaming for the travel eSIM line. This is required for it to use the local network, and it does not mean expensive home-carrier roaming — it simply lets the eSIM connect abroad.
5. Go back and set Cellular Data (default data line) to your travel eSIM.
6. To avoid accidental home charges, open your home line and turn its Data Roaming OFF.

On arrival: Android

1. Turn off Airplane Mode.
2. Open Settings and go to your SIM settings — Connections > SIM manager on Samsung, or Network & internet > SIMs on Pixel.
3. Select the travel eSIM and make sure it is turned on.
4. Set it as the preferred SIM for mobile data.
5. Open the eSIM’s settings and switch on Data roaming for that line.
6. Turn Data roaming OFF for your home SIM to prevent unwanted charges.

Why data roaming must be on for the eSIM

A travel eSIM works by connecting to local networks at your destination through your provider’s partners. To your phone, that counts as roaming, so the Data Roaming toggle must be on for the eSIM line or you will see no data. The key is to enable roaming only on the travel eSIM and keep it off on your home line — that way the eSIM carries your internet and your home carrier never racks up roaming fees. The correct combination is: home SIM roaming OFF, travel eSIM roaming ON, and default data set to the travel eSIM.

Should you activate before or on arrival?

Install early — a day or several days ahead is ideal so you are not troubleshooting in an airport. But in most cases activate (turn on the line and roaming) only when you land, so you do not waste plan time or trigger the start of a short validity window early. Some plans begin counting from first network connection and others from a set start date, so read the plan terms if timing matters for a short trip.

If it does not connect

• Restart the phone — this often forces it to find a local network.
• Check that the eSIM line is on, set as data line, and has roaming enabled.
• Try selecting a network manually in your network settings if automatic selection fails.
• Confirm you are within the plan’s coverage area and that the plan has started.

Set your calls and messages too

Data is only part of the picture. Decide which line sends your texts and makes calls before you travel so there are no surprises. Many travellers keep their home line as the default for calls and SMS — important for receiving bank and security codes — while routing all data through the travel eSIM. On iPhone this is set under Settings > Cellular by choosing a default voice line and a separate cellular-data line; on Android you set a preferred SIM for calls, messages, and data separately in your SIM settings. If your travel eSIM is data-only, it will not make normal phone calls at all, so leave voice on your home line and use internet-based calling apps where needed. Getting these defaults right once means you can simply land, switch on the eSIM, and go.

For background on how all this fits together, read what is an eSIM? When you are ready to buy, browse eSIM destinations such as Japan or the USA.