Glossary
The words on your eSIM, explained
Installing an eSIM throws a lot of acronyms at you, usually at the worst moment, when something is not working and support is asking for a number you have never heard of. One page per term, each answering one question.
The numbers support asks for
Three numbers that look alike and mean different things. The quickest way to tell them apart is their length.
- What is an ICCID?An ICCID is the 19 or 20 digit serial number of a SIM, physical or eSIM. Here is what it identifies, where to find it on your phone, and why support asks for it.
- What is an EID on a phone?The EID is the 32 digit identifier of the eSIM chip built into your phone. Here is how to find it, why an operator asks for it, and how it differs from the ICCID and the IMEI.
- What is an IMEI number?The IMEI is the 15 digit identity of your phone itself. Here is how to find it, what networks use it for, and why a dual SIM phone has two.
How an eSIM gets onto your phone
What is in a QR code, where the profile comes from, and what the settings do.
- What is an eSIM, and how do you use one abroad?An eSIM is a SIM card built into your phone. Here is how it works, how to check if your phone has one, and how it saves you money on roaming.
- What is an eSIM profile?An eSIM profile is the data that turns the chip in your phone into a working SIM. Here is what it contains, how many a phone can hold, and why deleting one is usually permanent.
- What is an LPA string?LPA:1$... is what an eSIM QR code actually contains. Here is how to read the three parts, when to type it by hand, and why it usually works only once.
- What is an SM-DP+ address?SM-DP+ is the server that holds your eSIM profile until your phone asks for it. Here is what it does, where the address comes from, and what it means when installation fails.
- What are APN settings?An APN is the doorway between your phone and the internet on a mobile network. Here is what it does, when you need to set one by hand, and why a wrong APN looks like no signal.
Words that decide whether a plan suits you
The terms that change what a plan can actually do once it is installed.
- What is data roaming?Data roaming is using mobile data on a network that is not your own. Here is what it costs, and why a travel eSIM needs it switched on while your home line needs it off.
- What is dual SIM?Dual SIM means two lines in one phone, which is what lets you keep your number while using a travel eSIM. Here is how it works and what the two lines can do at once.
- What is tethering?Tethering shares your phone's mobile data with a laptop or tablet. Here is how to turn it on, why it is sometimes blocked, and what it does to your allowance.
- What is a fair use policy (FUP)?A fair use policy is the limit hiding behind the word unlimited. Here is what it typically caps, how to read one before buying, and what happens when you cross it.
- What is VoLTE?VoLTE carries calls over the 4G network instead of 2G or 3G. Here is why it stopped being optional, and what it has to do with travelling.
Still stuck?
If something is not working rather than not clear, the troubleshooting guides go step by step instead of defining terms.