eSIM Glossary: Every Term Explained

eSIM terminology can be confusing, especially if you are new to the technology. This glossary defines every term you will encounter when buying, installing, and using a travel eSIM — in plain language with no unnecessary jargon.

Core eSIM terms

eSIM (embedded SIM): A SIM chip built permanently into your phone. It stores carrier profiles digitally, eliminating the need for a physical SIM card. Cannot be removed or swapped. Physical SIM (nano-SIM): The traditional small card you insert into your phone's SIM tray. Still used alongside eSIM in most phones for dual-SIM functionality. eSIM profile: A digital file containing carrier credentials — downloaded to your eSIM chip via QR code or app. Each profile represents one cellular plan. QR code (for eSIM): A scannable code provided by your eSIM provider after purchase. Scanning it downloads the eSIM profile to your phone. SM-DP+ address: A server address used for manual eSIM installation when QR code scanning fails. Your provider supplies this along with an activation code.

Network and carrier terms

Carrier / operator: A company that operates a cellular network — T-Mobile, Vodafone, KDDI, etc. eSIM providers partner with carriers to sell access to their networks. MVNO (Mobile Virtual Network Operator): A company that sells cellular service using another carrier's network. Most eSIM providers are MVNOs. Roaming: Connecting to a cellular network outside your home carrier's territory. Travel eSIMs are technically roaming — but you pay a flat rate, not per-MB charges. 4G LTE / 5G: Cellular network standards. 4G LTE delivers 10–100 Mbps. 5G delivers 100–1000 Mbps. Most travel eSIMs connect to 4G, though 5G is expanding. APN (Access Point Name): A gateway setting that connects your phone to the carrier's data network. Usually configured automatically by your eSIM; manual entry is sometimes needed on Android.

Plan and billing terms

Data plan / data bundle: A prepaid package of data (e.g., 5 GB for 30 days). You pay upfront and use until the data runs out or the plan expires. Unlimited plan: A plan with no stated data cap. May include fair-use throttling at very high volumes. Regional plan: A single plan covering multiple countries in a geographic region (e.g., Europe, Asia). See our regional vs country guide. Global plan: A single plan covering 100+ countries worldwide. Pay-as-you-go: A billing model where you pay per MB consumed rather than buying a fixed bundle. Drimsim uses this model. Top-up: Adding more data to an active plan, usually through the provider's app. Validity period: The number of days your plan remains active after first connection. Once expired, remaining data is lost. Tethering / hotspot: Sharing your phone's cellular data connection with other devices (laptop, tablet) via WiFi.

Phone and SIM terms

Dual SIM: A phone running two cellular plans simultaneously — typically one physical SIM and one eSIM. See our dual SIM guide. SIM lock / carrier lock: A restriction preventing your phone from accepting SIMs (including eSIMs) from other carriers. Contact your carrier to unlock. IMEI: A unique identifier for your phone hardware. Sometimes requested during eSIM activation. Find it in Settings → About Phone, or dial *#06#. IMSI: A unique identifier for your SIM/eSIM subscription. Stored in the SIM profile, not visible to users.