eSIM glossary: 40 terms in plain English
Buying and activating an eSIM comes with its own language. These are the 40 terms you will run into, each explained in one line.
The basics
- eSIM: digital chip built into your phone; installed with a QR code, no plastic.
- Physical SIM: the classic card; it coexists with the eSIM in the same phone.
- eSIM profile: the "file" that gets installed; each plan is one profile.
- Activation QR: code that downloads the profile; scanned only once.
- Activation: the moment the profile connects to a network for the first time.
- Dual SIM: using two lines at once (your number + the eSIM's data).
Settings
- Data line (default): which SIM uses the internet; while traveling, the eSIM.
- Data roaming: the switch that allows data outside the SIM's home country; on travel eSIMs it must be ON.
- APN: the network's technical address; it almost always configures itself.
- Network selection: picking a carrier manually when automatic fails.
- Airplane mode: turning radios off/on; the "soft reset" that fixes half of all problems.
- Reset network settings: wipes saved Wi-Fi and APNs; last resort before support.
Coverage and speed
- 4G/LTE: the standard travel network, enough for everything.
- 5G: faster; available depending on destination and plan.
- Local carrier: the destination network your eSIM uses (AT&T, Orange, NTT...).
- Multi-network: an eSIM that can attach to several carriers at the destination.
- Band: signal frequency; modern phones cover the travel bands.
- Coverage: where there is signal; almost always in cities, in remote areas it depends on the local carrier.
Plans and fine print
- Per-GB plan: you pay for a package (5, 10, 20 GB); when it runs out, top-up.
- Unlimited plan: no GB counter.
- Fair use: a clause that throttles speed after a certain usage (always read it).
- Throttling: the speed reduction itself.
- Top-up: buying more GB for the same profile.
- Validity: how many days the plan lasts from activation.
- Hotspot / tethering: sharing the phone's internet with a laptop or another phone.
Buying and support
- Compatibility: whether your phone accepts eSIM (iPhone XS+, Samsung S20+, Pixel 3+, and more).
- Unlocked phone: not tied to a carrier; a requirement for travel eSIMs.
- eKYC / registration: identity verification some countries require for local SIMs (the travel eSIM avoids it).
- LPA: the code/link that installs the eSIM without scanning a QR (one tap on iPhone).
- Refund: money back if the eSIM never connects; check the guarantee before buying.
- Invoice: proof of purchase; useful for business trips.
The ones that show up when things break
- "No service": the phone sees no network; almost always roaming off or a wrong manual network.
- "Invalid SIM": the phone is carrier-locked or the profile installed badly.
- PDP authentication failure: an APN error; fixed in settings.
- Endless "Activating...": the profile is waiting for a network; usually resolves at the destination or with airplane mode.
- Signal but no internet: attached to the network but no data; check data line and roaming.
- SOS (top right): emergency calls only; the phone found no usable network.
- Deleted profile: a removed eSIM usually cannot be recovered with the same QR; contact support.
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See my price →Frequently asked questions
What is the APN and do I need to configure it?
It is the network's technical address. In most cases it configures itself when the eSIM is installed; you only touch it manually if the internet won't start.
What does "fair use" mean in an unlimited plan?
That after a certain usage the provider may throttle your speed. VoaSim plans do not apply that policy.
What is data roaming and why must I turn it on?
It is the phone's permission to use data outside the SIM's "home" country. Travel eSIMs technically operate in roaming, so it must be ON.
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