Technical FAQ

A physical SIM is a removable plastic card containing a secure chip. An eSIM is a non-removable chip soldered to the device board, reprogrammable via remote provisioning. An iSIM (integrated SIM) integrates the SIM function directly into the main processor die, eliminating even the separate eSIM chip. All three use the same network authentication protocols; the difference is purely in hardware form factor and how credentials are managed.

SGP.22 is the GSMA's technical specification for consumer eSIM remote SIM provisioning. It defines the protocols, security requirements, and interfaces for the entire eSIM ecosystem — from the device's Local Profile Assistant to the SM-DP+ provisioning server. Compliance with SGP.22 ensures interoperability between devices from different manufacturers and profiles from different providers.

eSIM authentication uses the same AKA (Authentication and Key Agreement) protocol as physical SIMs, defined in 3GPP TS 33.102. The eUICC stores the subscriber's IMSI and Ki (authentication key). When connecting to a network, the network sends a random challenge; the eUICC computes a response using the Ki and a cryptographic function. This response authenticates the subscriber without ever transmitting the Ki over the air.

The eSIM profile download requires a TCP/IP connection to the SM-DP+ server. Before the eSIM is activated, the device has no cellular data connection, so Wi-Fi is the only available internet path. Once the profile is installed and activated, the eSIM provides its own cellular data connection independently of Wi-Fi.

During activation, the device transmits its EID (eUICC Identifier — a 32-digit unique identifier for the eSIM chip) and certificate chain to the SM-DP+ server. The server transmits the encrypted bound profile package back to the device. All communication is over HTTPS with mutual TLS authentication. The profile package itself is additionally encrypted with the eUICC's public key.

No. Each QR code is a single-use activation token. Once a profile has been downloaded to a specific eUICC, the activation code is invalidated on the server. This is a deliberate security measure to prevent profile duplication. If you need to install the same plan on a different device, you must request a new QR code from your provider.

PLMN (Public Land Mobile Network) selection follows 3GPP TS 23.122. When entering a new country, your device scans for available networks and compares them against the VPLMN (Visited PLMN) priority list in your eSIM profile. It selects the highest-priority available network. If no preferred network is found, it falls back to any available network. You can override this by manually selecting a network in your device settings.

Throttling occurs when you exceed the high-speed data allocation in your plan. The provider's network applies QoS (Quality of Service) policies that limit your throughput to a specified rate (typically 128 kbps–1 Mbps). To avoid throttling: monitor usage via the provider's app, use Wi-Fi for large downloads, and choose plans with adequate high-speed allowances for your usage patterns.

In most respects, yes. eSIM eliminates SIM swap attacks (where an attacker convinces a carrier to transfer your number to a new SIM) because the profile is cryptographically bound to your specific device hardware. Physical SIM theft is also not possible. The main residual risk is device theft, which exposes the active eSIM profile — mitigated by remote deactivation through your provider.

Force a PLMN reselection: toggle Airplane Mode on for 30 seconds, then off. If still no service, go to Settings → Cellular → Network Selection → disable Automatic → select an available network manually. If a specific network fails to register, try another. Restart the device if manual selection doesn't resolve the issue.

This typically occurs when: (1) you're in an area with poor 4G coverage and the device has fallen back to 3G, (2) your device's preferred network type is set to 3G/2G, or (3) the roaming partner network your eSIM is registered on only has a 3G roaming agreement. Check Settings → Cellular → Preferred Network Type and set it to 5G/4G/LTE. If the issue persists, try manually selecting a different network operator.