An eSIM (embedded SIM) is a small chip permanently soldered into a phone, smartwatch or tablet. Unlike a traditional SIM card you slide in and out of a tray, an eSIM stays in the device — you provision it by scanning a QR code or selecting a plan from a carrier's app.
How it works
The eSIM chip can hold multiple carrier profiles at once. When you activate Fuse, the carrier's provisioning server (called an SM-DP+) sends a digital profile to your phone over the internet, and your phone stores it on the eSIM hardware.
Why it matters
- Activate in minutes — no shop visit, no plastic in the post
- Switch providers without changing physical SIMs
- Run multiple lines on one device (e.g. work + personal)
- One less component to break or lose