esim

An eSIM, or embedded SIM, is a programmable SIM embedded in a device rather than a removable plastic card. It relies on an embedded Universal Integrated Circuit Card (eUICC) hardware component that stores one or more carrier profiles and supports remote provisioning of mobile network service.

Profiles are downloaded and managed over the air by the device or by the carrier via an eSIM management service. A device may hold multiple profiles and switch among them, often with one active profile at a time. Some devices support dual-SIM operation using an eSIM plus a physical SIM or multiple eSIM profiles.

Activation and provisioning are performed via secure, standardized workflows. The profiles contain network credentials and operator settings; provisioning uses secure elements and encryption. eSIMs are soldered into the device and are not intended to be user-removable, although some devices allow profile changes through software only.

Advantages include the ability to change carriers without swapping cards, easier provisioning for devices, space savings in small form factors, and improved suitability for IoT. It also enables remote carrier management and easier device lifecycle management across an enterprise.

Limitations include uneven carrier support, regional differences, and potential complications for locked devices or roaming agreements. Activation often requires data connectivity and a compatible device.

Standards and variants: eSIM is defined by GSMA and ETSI; the term also covers the future iSIM, where the SIM functionality is integrated into the device's main system-on-chip rather than on a separate chip.