What is an eSIM?
A plain explanation of eSIMs, how they differ from a plastic SIM, and what that means for travel.
A SIM without the plastic
An eSIM is a SIM card built into your phone. Instead of swapping a physical card, you download a mobile plan — called a profile — onto the chip that is already there. Most phones sold since 2018 can hold several eSIM profiles alongside a physical SIM.
Why it matters for travel
You can buy and install a data plan for your destination before you leave, then switch it on when you land. Your usual SIM stays in the phone, so your number keeps working for calls and messages while the eSIM handles data.
What onesim actually is
onesim is a data-only travel eSIM. You install it once and add packages to it for the places you visit — a country plan or a regional plan such as Europe (33 countries). It does not replace your home SIM and does not include a phone number.
Before you buy
Your phone needs to support eSIM and be carrier-unlocked. The compatibility check takes a minute and saves a refund later.