What an eSIM is
An eSIM is a SIM built into your phone that is programmed by software instead of by swapping a plastic nano-SIM card.
Most iPhones since the XS and most recent Android flagships support it, and many phones can hold several eSIM profiles at once.
Why it matters for switching
You can activate a new carrier in minutes, often while keeping your old line active, which makes testing coverage before you commit painless.
Travellers can add a local or regional data eSIM without losing their home number.
Things to check first
Your phone must be carrier-unlocked, and some prepaid brands still require a nano-SIM for the first activation.
Transferring an eSIM to a new handset needs a carrier-issued QR code or transfer flow, so keep account access handy.
This guide is general information, not advice about a specific account. Always check current terms on the carrier’s own website before signing up.