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Hardware & devices

SIM

The subscriber identity module, a secure chip that holds the credentials a device uses to authenticate on a mobile network, in removable card or soldered form.

A SIM is the small secure element that identifies a device to a cellular network. It holds a unique subscriber identity and a secret key, and performs the authentication exchange with the operator without ever exposing the key. In cellular IoT, the traditional plastic card is often replaced by an industrial-grade SIM in the same removable format, or by a soldered MFF2 chip that cannot fall out of a vibrating vehicle.

The operational question for a fleet is who controls the profile on the SIM. A classic SIM is locked to one operator, so changing carriers in a deployed device means a site visit. That constraint drove the development of the eSIM, which allows profiles to be downloaded remotely, and of connectivity management platforms for monitoring usage and switching plans at fleet scale.

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