eSIM Glossary: Every Term on the Checkout Page, Explained

Travel eSIM checkout pages are full of jargon, and some of it hides the terms that matter most. Here is what each word actually means.

The basics

• eSIM — a SIM card embedded in your phone. You add a plan by downloading a profile instead of inserting a card.
• Profile — the plan itself once downloaded onto the chip. One phone can hold several profiles and switch between them.
• EID — the serial number of the eSIM chip in your phone. Some providers ask for it; you will find it in your phone settings.
• ICCID — the identifier of an individual SIM profile. Support teams often ask for this when troubleshooting.
• QR code — how a profile is usually delivered. Scanning it installs the plan. It normally works only once.

Terms that affect what you actually get

• Fair-use policy (FUP) — the point at which an “unlimited” plan stops behaving as unlimited, usually a daily allowance. After it, your speed drops.
• Throttling — the deliberate speed reduction applied after a cap. 1 Mbps still runs maps and messaging; 128 kbps effectively ends useful data.
• Tethering / hotspot — sharing your data with a laptop or another phone. Often capped separately, and sometimes not allowed at all.
• Data-only — the plan gives internet but no local phone number, so calls and texts run through apps.
• Validity — how long the plan lasts. The clock normally starts at first connection, not at purchase, but not always — worth checking.
• Top-up — adding more data to an existing plan. Where it is not supported, running out means buying a whole new eSIM.
• KYC — identity verification. A few destinations legally require passport details before activation.

Coverage and network terms

• Local, regional and global plans — one country, a group of countries, or many. Regional plans usually beat buying several local ones on a multi-country trip.
• Host network — the local carrier your eSIM actually connects to. This, more than the brand you bought from, decides your real-world speed and coverage.
• MVNO — a provider that resells capacity on someone else's network rather than owning one. Most travel eSIM brands are MVNOs.
• Roaming — using a network other than your home one. Travel eSIMs roam by design, which is why the roaming setting must be switched on.
• 5G / LTE — the network generation available to your plan. A plan advertising 5G still depends on 5G existing where you are standing.