eSIM glossary

APN stands for Access Point Name: a setting that tells your phone which gateway to use for mobile data on a given network. Wrong APN = no internet, even with full signal bars.

Modern travel eSIMs configure the APN automatically when the profile installs. Occasionally — mostly on Android — the APN must be entered manually; the provider's installation email or help page lists the exact value.

If your eSIM shows signal but no data, checking the APN against the provider's documented value is one of the first troubleshooting steps.

A carrier lock (SIM lock) is a software restriction placed by the carrier that sold the phone, preventing it from using other networks' SIMs — including travel eSIMs. It is common on phones bought on installment plans.

A locked phone will usually refuse to install or activate a third-party eSIM profile, or install it but never connect. Checking the lock status before buying a travel eSIM avoids the most common "it doesn't work" scenario.

You can check under Settings (iPhone: General → About → Carrier Lock; Android varies) or by asking your carrier. Carriers must typically unlock phones that are fully paid off, on request.

A data-only eSIM provides mobile internet but no phone number — you cannot make regular calls or send SMS through it. The overwhelming majority of travel eSIMs work this way, which keeps them cheap and instant to provision.

In practice this is rarely a limitation: WhatsApp, FaceTime, Telegram and every other app work over data, and in a dual-SIM setup your home number remains reachable for traditional calls and texts.

If you specifically need a local phone number abroad (for local bookings or verification), you need either a local carrier SIM/eSIM or one of the few travel eSIMs sold with voice add-ons.

Dual SIM is a phone's ability to keep two lines active at once. For travel, the standard setup is: home SIM (physical or eSIM) stays on for calls and SMS — banking codes included — while a travel eSIM handles all mobile data.

Modern iPhones and most Android flagships support dual SIM as one physical SIM + one eSIM, or two eSIMs active simultaneously.

The key settings: set the travel eSIM as the data line, disable data roaming on the home SIM (so it cannot bill you), and leave the home line on for incoming texts.

An eSIM (embedded SIM) is a programmable chip soldered inside your phone, watch, or tablet that does the same job as a plastic SIM card: it identifies you to a mobile network. Instead of swapping a physical card, you download a "profile" from a carrier or travel eSIM provider — usually by scanning a QR code or tapping an activation link.

For travelers this matters because you can buy a data plan for your destination before you fly, install it over Wi-Fi at home, and come online the moment you land — while your home SIM stays in the phone for calls and texts.

Most phones released since 2018 support eSIM, including iPhone XR/XS and newer, Google Pixel 3 and newer, and recent Samsung Galaxy flagships. The phone must also be carrier-unlocked to use a third-party eSIM.

The profile is the actual "SIM" in eSIM form: a package of carrier data (your subscriber identity, encryption keys, network settings) downloaded into the phone's secure eUICC chip during activation.

Phones can store multiple profiles (commonly 5–10) but typically keep only one or two active at once. Old travel profiles can sit installed-but-disabled for future trips, if the plan supports reuse or top-ups.

Deleting a profile removes it from the phone permanently — most providers cannot restore a deleted profile to the same QR code, so disable rather than delete between trips unless you are sure the plan is finished.

eUICC stands for "embedded Universal Integrated Circuit Card". It is the tamper-resistant hardware element inside an eSIM-capable phone that can hold one or more carrier profiles and switch between them — the physical foundation that makes eSIM work.

When you buy a travel eSIM, the provider's system (an SM-DP+ server) delivers an encrypted profile to your phone's eUICC over a GSMA-standardized channel. The profile cannot be copied out of the chip, which is why eSIMs are considered harder to clone than plastic SIM cards.

You will sometimes see an "EID" — that is the unique serial number of your device's eUICC, which some providers ask for during activation.

A fair-use policy (FUP) is the fine print that governs how much you can really use a mobile data plan — most importantly on plans sold as "unlimited". A typical travel eSIM FUP grants a fixed amount of full-speed data per day (for example 1–3 GB), after which speeds are throttled until the next day.

FUPs exist because networks must manage congestion, and roaming agreements are priced per gigabyte. They are not inherently dishonest — but an unlimited plan's daily cap and post-cap speed matter far more than the word "unlimited".

Before buying, find the FUP in the provider's terms or help center and check three things: the daily high-speed allowance, the throttled speed after it, and whether hotspot use is restricted.

A global eSIM covers a very large set of countries — often 100 or more — on a single plan. It is the zero-thought option for complex itineraries, layovers, and round-the-world trips.

The tradeoff is price: global coverage almost always costs more per gigabyte than regional or single-country plans, because the provider must maintain roaming agreements everywhere.

Global plans also back remote and maritime niches: many cruise-capable and multi-region plans are technically global plans with satellite or at-sea partners.

Tethering — also called personal hotspot — lets your phone share its mobile data connection with other devices over Wi-Fi, Bluetooth, or USB. For remote workers it is often the single most important plan feature.

Not every travel eSIM allows it: some providers block tethering entirely, others allow it but count it against a daily fair-use cap. Plans on this site show a hotspot flag whenever the provider's data includes it.

Heavy tethering (a laptop doing video calls and cloud sync) consumes far more data than phone-only use — size your plan accordingly or pick an unlimited plan whose fair-use policy explicitly permits hotspot use.

KYC ("know your customer") is an identity check — passport or ID upload — required by regulators in some countries before a SIM or eSIM can go live. Destinations with strict SIM-registration laws may require it even for travel products.

Most international travel eSIMs avoid KYC because the plan is technically provisioned on a foreign network. But local eSIMs bought from in-country carriers, and travel eSIMs for a handful of strict markets, may ask for documents during checkout.

If a provider asks for ID, that is usually regulation rather than the provider being invasive — but it is also a reason privacy-conscious travelers compare who collects what before buying.

When a travel eSIM connects abroad, it is technically roaming on a partner network. During congestion some networks serve roaming traffic — including travel eSIMs — after their own customers, which can mean slower speeds at peak times in crowded places.

This "deprioritization" differs from throttling: it is situational, not a fixed cap, and disappears when the cell is less busy.

If speed is critical, look for plans that name the strongest local network as a partner, test with a speed test at your accommodation, and consider a backup eSIM from a provider using a different local network.

Validity is the lifespan of a travel eSIM plan: a "10GB / 30 days" plan gives you 10 GB to use within 30 days. When the window closes, unused data expires.

The crucial detail is when the clock starts. For most providers it begins when the eSIM first connects to a supported network at the destination — not when you buy or install it. Some plans, however, start on install or on a fixed date, so check the activation policy for long gaps between purchase and travel.

For long stays, compare topping up an existing plan versus buying a new one: top-ups often extend validity, while a new plan means reinstalling a profile.

Price per gigabyte is a plan's price divided by its data allowance: a $9 plan with 3 GB costs $3.00/GB. It is the fastest way to compare plans of different sizes fairly.

This entire site ranks plans by real price per GB after coupons, because sticker prices mislead: a cheaper plan with little data is often worse value than a slightly pricier one with triple the allowance.

Caveat: very large "unlimited-style" allowances can make price/GB look absurdly low without being meaningful — which is why our Price Index ranks countries by the cheapest plan with at least 1GB instead of raw price/GB.

After you buy a travel eSIM, the provider emails a QR code. Scanning it from Settings → Add eSIM tells your phone where to download the encrypted profile (the SM-DP+ address plus an activation code in one image).

Two practical rules: install over reliable Wi-Fi before you travel, and never scan eSIM QR codes from stickers, strangers, or unofficial websites — only from the provider's own email or dashboard.

Most QR codes are single-use: once installed on a phone, the same code will not install on a second device. If you delete the profile, many providers must issue a new code.

A regional eSIM bundles coverage for a group of neighboring countries — a "Europe 33 countries" or "Asia 12 countries" plan — so one profile works across borders without any action from you.

Regional plans usually cost slightly more per gigabyte than single-country plans but eliminate the hassle of buying and switching multiple eSIMs on one itinerary. They shine on trips crossing two or more borders.

Always check the covered-country list before buying: two "Europe" plans can cover different sets of countries, and popular add-ons like Switzerland, the Balkans, or Türkiye are not always included.

Roaming means your home carrier lets you use voice and data on a partner network abroad, billed through your normal account. It requires zero setup — and that convenience is priced in: international roaming is typically billed per day or per megabyte at rates far above local prices.

A travel eSIM replaces only the data side of roaming: you buy a local or regional data plan for the destination, while your home SIM stays active for calls and SMS. For most trips this costs a fraction of carrier roaming day passes.

Roaming still has legitimate uses: very short trips, destinations without eSIM coverage, or when you must keep your home number for incoming calls at all times.

SM-DP+ stands for "Subscription Manager – Data Preparation +". It is the server system, standardized by the GSMA, that encrypts a carrier profile and delivers it to the eUICC chip in your phone when you activate an eSIM.

The QR code you scan when installing a travel eSIM is essentially an address: it tells your phone which SM-DP+ server to contact and which profile to download. The download happens over an encrypted, mutually authenticated channel.

Travelers rarely need to know this term unless a provider asks you to enter an "SM-DP+ address" manually — an alternative to scanning the QR code that some Android phones and manual setups use.

Throttling means the network intentionally reduces your data speed. On travel eSIMs it usually happens after you exceed a daily high-speed allowance on an "unlimited" plan, or occasionally on specific traffic types like video streaming.

Typical throttled speeds range from 256 kbps to 1 Mbps. At those speeds, messaging, email, and basic maps still work; HD video streaming, video calls, and laptop tethering generally do not.

If your connection suddenly feels slow abroad, check whether you have passed your plan's daily cap before assuming a network problem — and run a speed test to see the actual number.

"Unlimited" on a travel eSIM rarely means infinite full-speed data. The near-universal industry pattern is a daily high-speed allowance (commonly 1–3 GB) followed by throttled speeds until the next day, defined in the plan's fair-use policy.

That structure is still valuable: you can never run out entirely, which suits travelers who cannot risk losing connectivity. But comparing unlimited plans requires reading the daily cap and post-cap speed, not just the headline.

Rule of thumb: if you know your usage, a large fixed-GB plan is usually better value; if you cannot afford to run dry, unlimited buys certainty.