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New Zealand“Virtual number”, “eSIM” and “second SIM” get used as if they were the same thing. They're not. They solve different problems, and picking the wrong one can mean paying for something that doesn't do what you need.
Here's what each one actually is, how they compare, and which one fits your situation.
Three technologies, three different jobs
- A virtual number is a phone number delivered over the internet. You make and receive calls and texts through an app or a web browser, on any device.
- An eSIM is a digital SIM card built into your phone. You download a mobile plan onto it instead of inserting a plastic card.
- A second SIM is a physical SIM card in the second slot of a dual-SIM phone.
The key difference: SIMs and eSIMs connect your phone to a mobile network. A virtual number connects a phone number to any device with internet.
What is a virtual number?
A virtual number works without a SIM card. Calls and texts reach you over Wi-Fi or mobile data, wherever you are. Some providers hand out internet (VoIP) numbers; others, like HeyNum, provide numbers from real mobile ranges, which apps and websites recognise as mobiles.
Good for: privacy, a work line, selling online, keeping a number from home, using one number on several devices.
Not for: mobile data, or emergency calls.
What is an eSIM?
An eSIM is simply a SIM card in digital form. There are two very different kinds of eSIM plans:
- Full mobile plans from a carrier, with a phone number, calls, texts and data — usually with a contract and an identity check.
- Travel eSIMs, which are almost always data only: perfect for using maps and messaging abroad without roaming fees, but with no phone number of their own.
Good for: mobile data abroad, or a full second line on one phone.
Not for: using a number on your laptop, or getting a number without paperwork.
What is a second SIM card?
A second SIM is a complete mobile line from a carrier: number, calls, texts, data and emergency calls. It needs a dual-SIM phone, and in most countries an ID check, a contract or a prepaid registration.
Good for: a full second line on one phone, including emergency calls.
Not for: using the line on several devices, or getting a number quickly.
Side-by-side comparison
| Virtual number | Travel eSIM | Second SIM / eSIM line | |
|---|---|---|---|
| Gives you a phone number | Yes | Usually not | Yes |
| Gives you mobile data | No | Yes | Yes |
| Works on a computer | Yes | No | No |
| Several devices | Yes | One phone | One phone |
| ID check | Not with HeyNum | Rarely | Usually |
| Setup time | Seconds | Minutes | Hours to days |
| Emergency calls | No | Data only | Yes |
Which one do you need?
- Travelling for a week or two? A travel eSIM for data. Add a virtual number if people need to reach you on a local number.
- Moving abroad? A local SIM or eSIM in your new country, plus a virtual number from home so family and services can still reach you.
- Want to keep your number private? A virtual number: give it out freely and switch it off when you like.
- Need a second full line on one phone? A second SIM or an eSIM line from a carrier.
Can you combine them?
Yes — and it's often the best setup. A typical traveller's phone today runs their home SIM for emergencies, a travel eSIM for cheap local data, and a virtual number in the browser for calls and texts that would otherwise cost a fortune in roaming. Each technology does the job it's best at.
Written by the HeyNum team. We build HeyNum, a service that gives you a real mobile number in your browser. We write about privacy, second numbers and staying reachable — and we're upfront when we mention our own product.
