What is an eSIM? - Roamly Support

An eSIM is a SIM card that’s already inside your phone. Instead of a plastic card you push into a tray, it’s a small chip on the phone’s board, and you download a mobile plan onto it. It does exactly what a normal SIM does; you just skip the card.

Why it’s good for travel

No shop, no queue. You buy the plan online and install it in a minute, anywhere you have internet.
Buy before you fly. Install at home, land connected.
Keep your normal SIM in. Nearly every eSIM phone is dual-SIM: your normal number stays active for calls and texts while the eSIM handles data abroad.
More than one at a time. Phones can store several eSIMs, so you can keep a Japan plan and a Europe plan on the same phone and switch between them.

Physical SIM vs eSIM

	Physical SIM	eSIM
Where it lives	A card in the tray	A chip built into the phone
Getting one	Buy a card, swap it in	Download a plan
Switching plans	Swap cards	Tap between profiles
Losing it	Easy to lose or damage	Nothing to lose

Do I need to take my normal SIM out?

No. Leave it in. The only settings that matter are which SIM your phone uses for data and whether roaming is on for your normal SIM (it should be off). The install guides cover both.

Does my phone have one?

Most phones sold since 2018 do, but a few don’t, and a phone locked to a carrier can’t use another provider’s eSIM. See Does my phone support eSIM?