Hoe werkt een eSIM?

After payment you receive a profile as a QR code or an activation string. Scanning it makes the phone download the profile from the operator's SM-DP+ server and store it as a second line. At your destination, enabling that line lets the phone attach to a partner network the same way a roaming SIM does.

The short version — that an eSIM works by downloading a profile from a server — is accurate, but it is the details of each step that trip travellers up, especially anyone who has never used an eSIM before and is not sure what needs doing before boarding a flight, what has to wait until arrival, and why some steps cannot be undone. This page works through the whole mechanism from purchase to the moment the phone actually attaches to a network at the destination, without quoting any speed figures or naming any network, since those details differ by provider and by destination.

This page is written for anyone about to buy their very first eSIM and wanting to know what to prepare, anyone who has already bought one but is hesitant to install it for fear of getting something wrong, and anyone who has installed it already but wants to understand why it needs enabling only at the destination rather than switched on back home. We work through each step without skipping the details that usually get overlooked.

What the QR code and activation code actually are

Once payment goes through, the system generates one identity file specific to that order, presented either as a QR code image to scan or as a long string of characters called the activation code, for typing in by hand. Both point to the exact same profile — they only differ in how the phone reads the information in. A QR code suits opening on a separate screen, such as a computer or a second phone, while the activation code suits typing directly on the phone that will actually use it.

Both the QR code and the activation code are typically single-use per device. Once the profile has been pulled into a phone, scanning it again on the same phone usually does nothing further, and scanning it on a different phone typically will not work since the profile is already tied to whichever device installed it successfully first. This is why it matters to confirm the code is being opened on the phone actually meant to use it, not tried out on another one by accident first.

What the SM-DP+ server actually does in this process

SM-DP+ is the name for the provider-side server that holds each order's eSIM profile, waiting for a phone to connect in and request it for installation. Scanning the QR code or entering the activation code is really the phone connecting to the internet, reaching this server, confirming the order's identity, and downloading the profile back to store on the device. This step needs working internet at the moment of installation, whether that is Wi-Fi or the data from whatever SIM is already active.

Because this step depends on the internet, installing is generally best done while still somewhere with a stable Wi-Fi connection, such as at home or in accommodation before travelling, rather than waiting to do it at the destination airport where Wi-Fi can be harder to find. Downloading the profile and enabling that line are two separate steps — the download can happen well ahead of time, while enabling it is what should wait until actually arriving.

Where the profile is stored, and how it becomes a second line

Once downloaded, the profile is stored on a dedicated chip inside the phone that works the same way a physical SIM card does, just without a visible tray. Most phones supporting eSIM today carry this chip alongside the original physical SIM tray, allowing genuinely two lines at once — one might be the original physical SIM carrying the main number, the other the newly installed eSIM profile for data while travelling.

Having two lines at once means setting which line handles calls, texts, or data. Most phones allow this to be set separately in the same menu that manages the eSIM. What is worth doing right after installing is opening that menu to confirm data is set to the new eSIM line, not still left on the original SIM — otherwise the original SIM's roaming data could quietly get used instead of the plan just bought.

The steps from purchase to actually getting online at the destination

1. 1Pay and receive the QR code or activation codeAfter payment goes through, check the email or order page to receive the QR code or activation code issued specifically for that order.
2. 2Install the profile while still on stable Wi-FiScan the QR code or enter the activation code while still somewhere with reliable Wi-Fi, since this step needs to download the profile from the provider's server.
3. 3Check the settings menu that the profile installed successfullyOpen the phone's eSIM management menu to confirm the new line appears on the list, even before it is switched on.
4. 4Wait to enable that line until reaching the destinationDo not enable the new data line while still at home; save that for arrival so the phone attaches to the right partner network in that country.
5. 5Enable the line and set data to point to itOnce at the destination, switch that eSIM line on in settings, set mobile data to use this line specifically, then give the phone a moment to attach to a signal.

Automatic activation versus enabling it yourself

Some plans start counting their validity the moment installation finishes; others start counting only from the first actual network connection. This difference matters a great deal, because enabling the line too early, before actually reaching the destination, could start the plan's clock running while it has not really been used yet. Which kind your own plan is should be checked directly on that plan's own details page, since it differs by provider.

If unsure whether the plan bought starts counting from installation or from the first real network connection, the safest approach is installing the profile ahead of time but leaving that line switched off, then enabling it only once actually at the destination. This approach works for nearly every kind of plan without needing to guess which rule applies.

How the phone attaches to a partner network on arrival

Once that eSIM line is switched on and the phone is in the destination country, it searches for a network the profile is authorised to use and connects to a partner network there automatically. This process closely resembles ordinary roaming with a local SIM, just using a digital profile instead of a physical card. Which partner network is actually available at a given destination depends on that plan provider's own agreements, and we do not name a fixed network here since it can change and differs by destination.

This process normally takes little time after switching on, though in some cases restarting the phone or toggling airplane mode can help prompt it to search for a signal again. If it has been switched on for a while with no signal appearing at all, restarting the phone is the first step worth trying before suspecting a problem with the profile itself.

Common terms encountered during installation and what they mean

What to do before travelling, and what must wait until arrival

Check the device supports it before starting

eSIM is not a function every phone has, and even the same model sold in a different country or through a different carrier can sometimes be locked against using eSIM. Before buying a plan, it is worth checking both the model and its lock status, since a phone that does not support it or is locked simply cannot install the plan at all.

Check whether your device supports eSIM

If the QR code will not scan or the code will not work

If scanning the QR code produces no response, try increasing the brightness on the device displaying it, or enlarging the image first, since sometimes it is simply a clarity issue rather than a broken code. If that still fails, switch to entering the activation code manually instead — it uses the exact same information, just typed in rather than scanned.

If neither method works at all, do not rush to buy another plan — most issues encountered can be resolved without buying again. Message us on LINE or by email with the order name and exactly what is happening, and we can help check whether the profile is still usable.

Checklist before starting installation

• Confirm the phone supports eSIM and is not locked to a previous carrier
• Connect to stable Wi-Fi before starting installation
• Open the QR code or activation code from the email or order page
• Install the profile but hold off enabling the line until reaching the destination
• Label the line clearly so it is not confused with the original SIM
• Check settings that data points to the new eSIM line once arrived

Read the detailed eSIM installation guide