An eSIM is a SIM card that is built into your phone rather than pushed into a tray. Instead of waiting for a piece of plastic to arrive, you download a small file called a profile, usually by scanning a QR code, and the number is live in a few minutes. Because the eSIM is separate from your physical SIM, you can hold two numbers on one phone without changing anything about the number you already use.
How an eSIM actually works
Every SIM card is really just a tiny secure chip that proves to a mobile network who you are. A plastic SIM carries that chip around; an eSIM is the same chip, soldered into the phone at the factory, able to be written and rewritten over the air.
When you buy a number from us, we hand you a QR code. Scanning it tells your phone where to fetch the profile from, and your phone downloads it over wifi. Once the profile is on the phone, your handset behaves exactly as if you had inserted a second SIM card.
eSIM vs plastic SIM
| Plastic SIM | eSIM | |
|---|---|---|
| How you get it | Posted, or picked up in a shop | Downloaded by scanning a QR code |
| Time to be up and running | Days, usually | Minutes, usually |
| Where it lives | In the SIM tray | On a chip inside the phone |
| Can you hold a second number? | Only if the phone has two trays | Yes, alongside your existing SIM |
| If you lose the phone | The card can be moved to a new phone | The profile is re-downloaded to a new phone |
What people use a spare eSIM for
The most common reason is simply wanting a second number that is not your everyday one. That might be so you can run a separate WhatsApp account or a second Telegram account, or so you have a number you are happy to give out to strangers, marketplaces and sign-up forms.
- A number for selling things online, so buyers never see your personal one.
- A number for work, kept apart from friends and family.
- A separate messaging account, registered to its own number.
- A number you can hand over on a form without a second thought.
It sits beside your main SIM, not instead of it
This is the part worth repeating: adding a spare eSIM does not touch your existing number, contract, or the way you make calls today. Your main line stays your default for calls and data unless you deliberately change it. See dual SIM explained for how the two lines share one phone.
Is an eSIM number a real mobile number?
Yes. The numbers we sell are real UK mobile numbers beginning 07, running on a real mobile network. They ring, they receive texts, and they receive verification codes in the ordinary way. That matters, because plenty of services quietly reject virtual and internet-calling numbers when you try to sign up. There is more on that in receiving verification codes on your spare number.
The number is ordinary. The way it arrives on your phone is the only unusual part.
Getting started
- 1Check your phone supports eSIM and is unlocked: does my phone support eSIM?
- 2Pick a plan: see the WhatsApp plan or see the Telegram plan.
- 3Scan the QR code we send you and label the new line "Spare".
- 4Leave your main line as the default so nothing changes day to day.
eSIM Chat is powered by eSIM Copilot and part of Mindszi. You can read more on our about us page.
Common questions
Do I need to remove my current SIM to use an eSIM?
No. The eSIM lives on a separate chip inside the phone, so your existing SIM stays where it is and keeps working exactly as before.
Does an eSIM use more battery?
Running two active lines can use slightly more battery than one, because the phone maintains two network connections. In normal use most people do not notice a difference.
What happens to my eSIM if I change phone?
An eSIM profile is tied to the phone it was installed on, so moving to a new handset means installing the profile again on the new phone rather than moving a card across. Get in touch and we will reissue it.
Is an eSIM number the same as an internet calling number?
No. Internet calling and virtual number apps route calls over data and are often blocked at sign-up. An eSIM number is a real mobile number on a mobile network, which is why verification codes reach it normally.
Get a spare number
A real UK line that lives on your phone as an eSIM, beside the SIM you already have. Installed in minutes.