Register, install & use
When should you install your eSIM? Install vs. activation
3 min read · Updated September 19, 2026
Installing an eSIM and activating it (starting data) are two different things. It's safest to install ahead of time on a stable internet connection, and to activate (turning on data/roaming) after you arrive. When the validity period starts, though, varies by product (most start when you connect to a local network, some the moment you install), so check the plan's validity policy before buying.
Install and activation are different
Installing means downloading the eSIM profile onto your phone; activating means actually starting to use data (turning on data/roaming). These happen at different times. Installing does not immediately consume your data.
Install early, activate after you arrive
If you have stable Wi-Fi, it's safest to install about a day before you leave. That avoids failing to install over a crowded, unstable airport Wi-Fi at your destination. Do the activation (turning on data/roaming) after you arrive.
When does validity start counting down? (important)
When the validity period begins varies by product. For most, it starts when the eSIM first connects to a network in its coverage area; for some products, it starts the moment you install it. That's why it's best to check the plan's validity policy before buying or installing.
Watch out for plans that cover your departure country
- Global and regional eSIMs may include your departure country (e.g. Korea) in their coverage
- In that case, turning on data before you leave can attach to a network at home and start using up validity
- Install early, but turn on data/roaming only after you reach your destination
FAQ
Can I install it before I leave?
For most plans, yes (it's actually recommended). Installing and the start of validity are separate, so validity usually doesn't start until you turn on data after arriving. Some products start the moment you install, though, so check the plan details before buying.
Can I install over airport Wi-Fi?
You can, but crowded airport Wi-Fi can be unstable, so it's safer to install ahead of time on a stable connection like your home internet.
When does the validity start counting down?
It varies by product. For most it's when you first connect to a local network; for some it's the moment you install. Check the plan's validity policy before buying.