eSIM glossary

Plain-English definitions for the 22 terms you'll run into when buying travel data.

APNAccess Point Name: The settings that let your phone connect to a carrier's mobile data network. Roamjoy eSIMs configure this automatically.
Carrier-unlocked: A phone that isn't tied to a single network, so it can use eSIMs and SIMs from any carrier. Required to use Roamjoy.
Data roaming: Using mobile data on a network other than your home carrier's, usually while abroad. Your Roamjoy line needs data roaming switched on.
Dual SIM: A phone that runs two SIMs at once — for example your home SIM for calls and a Roamjoy eSIM for data.
EIDEmbedded Identity Document: The unique serial number of the eSIM chip built into your device.
eSIMEmbedded SIM: A digital SIM built into your device. You install a plan by scanning a QR code — no physical card to swap.
Great Firewall: China's system of internet filtering that blocks many foreign sites and apps. A VPN is often needed to reach them.
Hotspot / tethering: Sharing your phone's mobile data with other devices over Wi-Fi, Bluetooth, or a cable.
ICCIDIntegrated Circuit Card Identifier: The unique number that identifies your specific SIM or eSIM profile.
IMEIInternational Mobile Equipment Identity: The unique serial number of your phone's hardware, used to identify the device on a network.
LTELong-Term Evolution: The 4G mobile data standard — faster than 3G and the baseline for most eSIM plans.
MNOMobile Network Operator: A carrier that owns and runs its own network infrastructure.
MVNOMobile Virtual Network Operator: A carrier that resells capacity on another operator's network rather than owning its own.
PIN code: A short numeric code that can lock a SIM. Most eSIM profiles don't require one.
QR code: The scannable square code that installs your eSIM profile onto your device.
Roaming: Using your phone on another carrier's network outside your home coverage area.
SM-DP+: The secure server that prepares and delivers eSIM profiles to your device during installation.
Tier-1 carrier: A top-tier national network with the broadest coverage and fastest speeds in its country.
Top-up: Adding more data or a new plan to an existing eSIM once your allowance runs low.
Unlimited data: A plan with no fixed data cap, though speeds may be managed under a fair-use policy.
VoIPVoice over IP: Making calls over the internet — for example WhatsApp or FaceTime — instead of a traditional phone line.
VPNVirtual Private Network: A service that encrypts your connection and can make it appear you're browsing from another country.