Beginner's eSIM guide: from what it is to getting online on arrival

What is an eSIM?

An eSIM is a SIM card embedded on the phone's motherboard; you don't need to eject the tray and insert a physical card, instead you download a network profile to the phone. Once installed, the device connects to the local network at the destination, and works exactly the same as if you had inserted a local SIM card.

It's important to understand: eSIM is just a 'delivery method', not a specific telecom operator. The network it uses is still the destination's local operator — the same plan, whether you use an eSIM or a physical card, the network is the same, only the installation method differs.

From payment to usage, there are several steps: payment, obtaining a QR code, installation, activation. The step-by-step process is explained in How it works; reviewing it before ordering will save you a lot of trouble.

Difference between eSIM, physical SIM and roaming

If your phone is dual-SIM, eSIM and physical card are similar in function; the real differences are 'how you receive it' and 'whether your device supports it'; roaming is a completely different logic.

Check two things before ordering: EID and network lock

First, check whether your device supports eSIM: dial *#06#; if the screen shows an EID line in addition to IMEI, the hardware supports eSIM; if only IMEI appears, it does not support eSIM, so switch to buying a physical card.

One special case to note: some batches of mainland China‑version iPhones lack eSIM hardware. If you have a mainland China model, dial *#06# to confirm before ordering; don't assume it will work.

Second, check for network lock: a device locked to a particular carrier (only works with that network) cannot use another carrier's eSIM; you must unlock it with the original provider first. You can check the full list of supported devices on Compatible devices.

Installation and activation are two different things; the plan period starts from the first connection.

Installation means scanning the QR Code to write the eSIM profile onto the device. This can be done over home Wi‑Fi, no need to wait until you land. After payment, the line is activated in about 30 seconds and the QR Code can be scanned right away.

Note: the QR Code can generally be scanned only once and is consumed after use. So before scanning, double‑check the plan, destination and validity period; don't scan in a hurry.

Activation (the start of the plan period) is another matter: the days are counted from the first time the device connects to a local network, not from the time of payment or installation. So installing early does not waste days — a 7‑day plan will not start counting down at home, it only begins when the device first connects to a network on arrival.

Daily data cap, total data cap or unlimited — which to choose?

Daily quota is a fixed daily allowance (e.g. 1GB); if you use it up for the day, speed will be reduced, and it automatically refills the next day; any unused data does not carry over. The total data plan is a single pool for the whole trip, so you can use more on some days and less on others, which is more flexible. For the differences between the two billing methods and which trips they suit, see Daily quota vs total data.

Quick guide: if your trip is focused, mainly for navigation, looking up information, and messaging via app, the daily quota is usually enough; if you need to reuse data heavily every day (streaming, hotspot, uploading lots of photos), choose the total data plan or a higher tier.

‘Unlimited’ needs careful reading: most ‘unlimited’ plans are ‘unlimited after using X high‑speed data, then speed is reduced’, not truly unlimited; how much high‑speed data you get depends on the plan details. Estimating data usage is not difficult: 1080p streaming uses roughly 1GB per hour (industry standard estimate), actual usage can be adjusted according to your own habits.

Pre‑departure checklist

Once everything is checked, go to the corresponding destination page to place an order, for example Japan; the eSIM is activated immediately after payment, no need to wait for mailing.

• Dial *#06# to confirm the presence of an EID (device supports eSIM); a locked phone must be unlocked.
• Order one or two days before departure, the card is activated about 30 seconds after payment, and you will receive the QR Code.
• Install via Wi‑Fi before departure: the QR Code can generally only be scanned once, verify the plan and validity before scanning.
• On first use after landing, turn on data roaming for your eSIM and simultaneously turn off data roaming on your original SIM card to avoid being charged on both sides.
• No need to worry about installing early and wasting days; the days start from the first time you connect to the local network.