eSIM

eSIM is a standardized, embedded SIM chip soldered into a device’s motherboard that stores carrier profiles in reprogrammable firmware. Unlike a removable SIM card, it can hold multiple profiles simultaneously and switch between them via software. The GSMA specification governing eSIM interoperability has made it standard in most flagship smartphones, tablets, and wearables since around 2018.

How it works

When a user purchases an eSIM plan, the carrier generates a QR code or activation code that encodes an SM-DP+ (Subscription Manager Data Preparation) server address and an activation token. The device connects to that server over HTTPS, authenticates, and downloads the carrier profile, which is then installed and activated on the embedded chip. Multiple profiles can coexist, with only one (or two on Dual SIM devices) active at a time.

Key facts

• Standards body: GSMA SGP.22 defines the consumer eSIM remote provisioning specification
• Profile storage: Most devices can store 5 to 20+ eSIM profiles simultaneously, though limits vary by manufacturer
• Physical size: The embedded chip is typically an MFF2 form factor, about 5mm x 6mm, soldered directly to the board

For builders

For builders who travel frequently, eSIM removes the friction of hunting for a local SIM card on arrival. Providers like Airalo, Nomad, and Holafly sell regional or country-specific data plans that activate in minutes via QR code. The ability to keep a home number active on one profile while running a local data eSIM on another makes it the default connectivity strategy for most digital nomads.

Sources

• GSMA. eSIM specifications SGP.21 and SGP.22 for consumer Remote SIM Provisioning. gsma.com
• GSMA. The State of the eSIM Market whitepaper. gsma.com
• ITU. Recommendation E.118: International telecommunication charge card / ICCID structure. itu.int
• 3GPP. Mobile network specifications portal. 3gpp.org
• FCC. Consumer guides on wireless devices and unlocking. fcc.gov