Glossary
Every eSIM and connectivity term you will meet while planning a trip, defined in plain language.
4G LTE
4G LTE is the fourth generation of mobile network technology, delivering fast data speeds suitable for streaming, maps and video calls while travelling.
5G
The fifth generation of mobile network technology, delivering faster speeds and lower latency than 4G LTE where plan, network and phone all support it.
Activation code
The SM-DP plus server address and matching ID encoded in an eSIM QR code, which your phone uses to download and install the eSIM profile.
APN (Access Point Name)
The setting that tells your phone which gateway to use on a mobile operator's data network; a wrong or missing APN means signal but no mobile data.
Band compatibility
Whether a phone's radio frequencies match the ones local networks broadcast; without an overlap you get weak signal or none at all abroad.
Carrier lock
A software restriction tying a phone to the network that sold it, blocking SIMs and eSIMs from other operators until the lock is removed.
Data roaming
The per-line phone setting that permits mobile data on networks other than your home carrier's; travel eSIMs usually need it switched on to work.
Data-only eSIM
An eSIM that gives you mobile data but no local phone number and no traditional calls or texts; ideal for maps, apps, and staying online abroad.
Dual SIM
A phone feature that lets two SIM lines work at once, physical or eSIM, so your home number stays reachable while a travel eSIM handles data.
EID
The EID is the unique 32-digit identifier of your device's built-in eSIM chip; seeing one in your settings or by dialling *#06# confirms your phone can run a travel eSIM.
eSIM
A digital SIM built into your phone that lets you download a mobile plan over the internet instead of inserting a physical SIM card.
eSIM conversion
eSIM conversion means turning a physical carrier SIM into a digital eSIM on the same number; travel eSIMs, by contrast, are eSIM-only and cannot become a physical SIM.
eSIM profile
The downloadable data package containing operator credentials that an eSIM chip stores; one chip can hold several profiles from different providers.
eSIM transfer
eSIM transfer is the process of moving an eSIM profile from one device to another, either with a built-in transfer tool or by reinstalling the profile on the new phone.
Fair usage policy (FUP)
A fair usage policy (FUP) is a set of rules that limits how much high-speed data you can use on an unlimited or large plan before speeds are reduced.
ICCID
The unique 19 to 20 digit serial number that identifies a single SIM card or eSIM profile, used by support and networks to look up your line.
IMEI
A unique 15-digit number that identifies your handset to mobile networks; used to check carrier locks, register devices and block stolen phones.
IMSI
The number that identifies your subscriber line on a mobile network, letting operators authenticate you and route calls, texts, and data while roaming.
iSIM
A SIM built directly into a device's main processor rather than a separate chip; the next step in SIM miniaturisation after the eSIM.
LPA
The software built into your phone that finds, downloads, and installs eSIM profiles; it reads the activation string that starts with the LPA:1 prefix.
Mobile hotspot (tethering)
A phone feature that shares its mobile data connection with other devices over Wi-Fi, Bluetooth or USB, turning one eSIM into internet for many devices.
MVNO (Mobile Virtual Network Operator)
An MVNO (Mobile Virtual Network Operator) is a carrier that sells mobile service using another operator's physical network rather than building its own towers.
Network coverage
Network coverage is the geographic area in which a mobile network provides a usable signal, determining where your phone can make calls and use data.
Network selection
Network selection is the process by which a phone chooses which mobile network to connect to, either automatically or manually from a list of available carriers.
PLMN
A mobile operator's unique numeric network code; your phone uses it to identify and, when set manually, lock onto a specific partner network abroad.
QR code installation
The standard way to set up an eSIM: scanning a provider QR code makes your phone download the eSIM profile automatically in a couple of minutes.
Regional eSIM
A regional eSIM is a single travel eSIM that provides mobile data across multiple countries in one region, such as Europe, without switching plans at each border.
Roaming
Using a foreign mobile network while abroad, with your home carrier billing you for it, often at rates far higher than local or prepaid eSIM plans.
SIM registration
SIM registration is a legal requirement in some countries to link a SIM card or eSIM to a verified identity, usually a passport, before it can be used.
SM-DP+
A remote server that securely stores your eSIM profile and hands it to your phone during install; the QR code just points your device at its address.
Tethering
Sharing one device's mobile data connection with a laptop or another gadget over USB, Bluetooth or a wifi personal hotspot.
Throttling
Throttling is the deliberate slowing of your mobile data speed by a provider, usually after you pass a usage limit set out in a fair usage policy.
Top-up
Adding more data or extra validity to an eSIM plan you already installed, rather than buying and installing a brand new plan.
Unlocked phone
A phone not tied to any single operator, so it accepts a SIM or eSIM from any network; needed for a travel eSIM to connect abroad.
Validity period
A validity period is the length of time a prepaid eSIM or data plan stays usable, usually counted in days from activation or first connection to a network.
VoLTE
Voice over LTE lets your phone make and receive calls over the 4G data network instead of an older 2G or 3G circuit.
VPN
A VPN (virtual private network) is a service that encrypts your internet traffic and routes it through a remote server, masking your activity and location.
Wi-Fi calling
Wi-Fi calling is a phone feature that routes voice calls and texts over a Wi-Fi connection instead of the mobile network, using your existing phone number.