Technical FAQ

SGP.22 is the GSMA's technical specification for consumer eSIM remote provisioning. It defines the architecture, interfaces, and security requirements for downloading and managing eSIM profiles. Devices and platforms compliant with SGP.22 can interoperate with any compliant provider, ensuring portability and security. When evaluating eSIM providers, GSMA certification is a baseline quality indicator.

An eSIM is a dedicated reprogrammable chip soldered to the device motherboard. An iSIM (integrated SIM) integrates SIM functionality directly into the device's main application processor or SoC (System on Chip). iSIM reduces physical footprint and power consumption but is still emerging in consumer devices. Both use the same GSMA provisioning standards.

eUICC (embedded Universal Integrated Circuit Card) is the hardware component that enables eSIM functionality. It is the chip that stores carrier profiles and executes the cryptographic operations required for secure profile management. When people say "eSIM," they typically mean the combination of the eUICC hardware and the SGP.22 software specification.

The SM-DP+ (Subscription Manager Data Preparation Plus) server is responsible for preparing, storing, and delivering eSIM profiles to devices. The reliability and geographic distribution of a provider's SM-DP+ infrastructure affects activation speed and success rates. Providers using certified, redundant SM-DP+ infrastructure from established vendors offer more reliable provisioning experiences.

Network steering is the configuration that determines which local network your roaming device connects to in each country. eSIM profiles contain a Preferred PLMN (Public Land Mobile Network) list that guides network selection. The quality of this steering configuration — specifically, whether it directs you to the best available network in each location — significantly affects your connectivity experience.

EU Roaming Regulation (Regulation 531/2012, as amended) requires that EU carriers allow their customers to roam across EU member states at domestic prices, subject to fair-use policies. Technically, this is implemented through bilateral roaming agreements between carriers, with the EU regulation setting the maximum wholesale rates carriers can charge each other. The quality of the roaming experience depends on the specific bilateral agreements in place.

VoLTE (Voice over LTE) enables voice calls over 4G networks rather than falling back to 2G/3G. For travelers, VoLTE support on roaming connections affects call quality and battery life. Not all eSIM providers support VoLTE on roaming connections, and support varies by country and network partner. If voice calls are important, verify VoLTE roaming support before selecting a plan.

In home routing, your data traffic is routed back to your home network before reaching the internet, increasing latency. In local breakout, traffic exits to the internet locally in the visited country, reducing latency. EU regulations mandate local breakout for EU roaming, but travel eSIM plans may use different architectures. Local breakout generally provides better performance for latency-sensitive applications.

Data throttling is implemented at the carrier level through policy control functions that monitor data usage per subscriber. When a usage threshold is reached, the carrier applies a QoS (Quality of Service) policy that limits the data rate. For eSIM plans, throttling may be applied by the home network (the eSIM provider's network) or by the visited network, depending on the roaming architecture.

On iOS: Settings → General → About → look for EID (eSIM Identifier). On Android: Settings → Network & Internet → SIM cards → look for eSIM option. The presence of an EID confirms eSIM hardware support. Note that some devices have eSIM hardware but with functionality disabled by the carrier — check your carrier's eSIM policy separately.

A carrier-locked device can only use SIM profiles from the locking carrier or its approved partners. This restriction applies to eSIM profiles as well as physical SIMs. Devices purchased through carrier subsidies are often locked. Unlocking requirements vary by carrier and jurisdiction. In the EU, carriers must unlock devices upon request after the contract period. In the US, policies vary by carrier.

The number of storable eSIM profiles depends on the eUICC hardware and device firmware. Most modern devices can store 5–20 profiles, though only one (or two on dual-SIM devices) can be active simultaneously. Some providers implement single-use profiles that are deleted after use, while others allow profiles to be retained and reactivated.

Digital nomads spending extended periods in a single country typically benefit from local SIM cards or local carrier plans, which offer better value and network quality than travel-specific eSIM products. For nomads moving frequently, a high-data eSIM plan covering primary destinations, supplemented by local SIMs for extended stays, provides the best balance.

Cross-border train travel typically results in brief signal interruptions as your device switches between national networks. For eSIM users with multi-country plans, this transition should be automatic. Ensure your plan covers all countries on your route, and verify that the plan includes the specific countries you will transit through, not just your origin and destination.

Business travelers requiring reliable video conferencing should prioritize: (1) a provider with documented Tier-1 network partnerships in their destination countries, (2) a plan that does not throttle speeds during peak hours, (3) VoLTE support if voice calls are needed, and (4) 24/7 customer support with rapid response times. Consider maintaining a backup connectivity option for critical meetings.