Virtual SIM Card Explained: eSIM, Virtual Numbers and iSIM

A virtual SIM card usually means an eSIM: an electronic SIM built into your phone that you set up by downloading a plan instead of inserting a plastic card. But the phrase is also used for virtual phone number apps, which give you a second number over the internet, and for iSIM, a newer kind of digital SIM built into a device's processor. They do very different jobs, so it is worth knowing which one you actually need.

Last checked: 27 October 2026. Phone support for eSIM and iSIM changes with each new model, so check your phone maker's or network's own pages before you buy.

Three things people call a virtual SIM

Search for an e SIM card, an electronic SIM card or a digital SIM card and you will find all three of these mixed together:

• eSIM (embedded SIM). A SIM chip soldered inside your phone. You download a profile from a mobile network, which gives you a real mobile connection: data, and on a phone plan, a number too. This is what UK networks and travel eSIM providers sell.
• Virtual phone number apps. Apps that give you an extra phone number which works over the internet (VoIP). They are not a SIM at all. You still need mobile data or Wi-Fi from somewhere for them to work.
• iSIM (integrated SIM). The SIM function built into the device's main chip rather than a separate one. For users it behaves like an eSIM. So far it is used mainly in connected devices such as trackers and wearables, and we could not confirm any mainstream phone sold in the UK that uses one for consumer plans.

Our guide to what an eSIM is and how it works explains the technology behind eSIM and iSIM in more depth. This article focuses on what each option does for you.

Virtual SIM options compared

eSIM: the electronic SIM card in your phone

If you have an iPhone XR or later, a recent Samsung Galaxy or a Google Pixel, your phone almost certainly has an eSIM chip already. You do not buy an "e SIM card" as a physical object. You buy a plan, and the plan is downloaded to the chip. The quickest test is to dial *#06#: if you see an EID number, your phone has eSIM. You can also look up your model with our device compatibility checker.

Most UK networks now offer eSIM versions of their plans, and it works the same as a normal SIM: same number, same allowance, same coverage. For a fuller look at the trade-offs, see eSIM vs traditional SIM: pros, cons and future trends.

Travel eSIMs give you data, not a number

A travel eSIM is a data-only plan. It connects you to a local partner network abroad, so you can use maps, messaging, email and banking apps at local data prices, but it does not give you a new phone number for ordinary calls and texts.

That is usually what you want. Your UK SIM stays in the phone, so you can still receive texts from your bank, while the travel eSIM handles data. Turn off data roaming on your UK line so it does not run up charges. Our dual SIM settings guide walks through it step by step.

WhatsApp keeps working with your UK number too, because your WhatsApp account is linked to your number, not to whichever SIM is providing data. Our guide to keeping your WhatsApp UK number with a travel eSIM explains how.

Virtual number apps: a second number, not a SIM

Virtual number apps can be useful if you want a separate number for work, selling online or keeping your personal number private. They are not a replacement for mobile data, though:

• They need an internet connection. Abroad, that means Wi-Fi, a travel eSIM, a local SIM or roaming on your UK plan.
• Some services may not accept them. Banks and other services that send security codes by text may not send them to an internet-based number, so keep your UK SIM active for those.
• Emergency calls. Do not rely on an app number for emergencies. Use your phone's normal dialler. In the EU, 112 is the free emergency number (European Commission), and it also works in the UK alongside 999.

If what you really want is to stay reachable on your UK number abroad, you probably do not need a virtual number at all: a travel eSIM for data plus WhatsApp or FaceTime does the job.

iSIM: the next step for digital SIM cards

iSIM moves the SIM into the device's main processor, which saves space and power. The GSMA, the mobile industry body that sets SIM standards, has certified iSIM designs, and you can read its overview of embedded SIM technology on the GSMA eSIM page. When iSIM does arrive in phones, plans are expected to install the same way as eSIM plans, so travel eSIMs should work on it. For now, if your phone has eSIM, that is all you need.

Which one do you need for travel?

• You want mobile data abroad without roaming charges: a travel eSIM.
• You want to keep getting UK calls and texts: keep your UK SIM on alongside the eSIM.
• You want a separate number for work or privacy: a virtual number app, used over Wi-Fi or a data plan.
• Your phone has no eSIM: a physical SIM, either a local one or an international SIM card. See our guide to international SIM cards vs travel eSIMs.

SimplySIM travel eSIM prices

SimplySIM sells data-only travel eSIMs for single countries, regions and worldwide trips, paid in pounds. On 27 October 2026, SimplySIM plans included:

The Europe plans cover 34 countries and areas, and Global Plus covers 127. See all regional and global eSIMs, or start from a country page such as Spain or Japan.

FAQs

What is a virtual SIM card?

Usually it means an eSIM, a SIM built into your phone that you set up by downloading a plan. The term is also used for virtual number apps, which give you a second number over the internet, and sometimes for iSIM.

Is an e SIM card the same as an electronic SIM?

Yes. eSIM, e SIM, electronic SIM and embedded SIM all mean the same thing: a SIM chip built into the device that stores downloadable plans.

Can I get an eSIM in the UK?

Yes. Most UK networks offer eSIM versions of their plans, and travel eSIM providers such as SimplySIM sell data eSIMs for use abroad. Your phone needs to support eSIM and be unlocked.

Does a virtual SIM give me a phone number?

It depends on the type. A UK network eSIM includes your number. A travel eSIM is data only. A virtual number app gives you a separate number, but it needs data or Wi-Fi to work.

Can I use WhatsApp with a travel eSIM?

Yes. WhatsApp stays linked to your UK number, and the travel eSIM just provides the data it runs on. Keep your UK SIM in the phone so you can still receive texts.

Do digital SIM cards work abroad?

A travel eSIM is designed for abroad. A UK network eSIM works abroad on your network's normal roaming terms, which may include daily charges. Virtual number apps work anywhere you have an internet connection.