How it works
How virtual phone numbers work, in plain English
A virtual number is a real phone number that rings in an app instead of on a SIM. Here is what happens when someone calls it, what "local" and "mobile" mean, and what the number can and cannot do.
The word "virtual" makes it sound as if the number is not quite real. It is. A virtual number is an ordinary phone number from a country's numbering plan; what differs is where it rings. Instead of being tied to a SIM card in one handset, it is tied to an account and delivered to an app.
What happens when someone calls
- The caller dials the number from any phone, as normal, and their carrier hands the call to the network that holds the number.
- That network knows the number belongs to a service rather than a SIM, and passes the call to the service over the internet.
- The service routes the call to the account that owns the number, and the app on your phone rings, over Wi-Fi or mobile data.
- You answer in the app. Your voice travels back the same way.
Texts follow the same path, arriving in the app rather than in your phone's SMS inbox. When you call or text out, the process runs in reverse, and the person you call sees the virtual number.
Local, mobile, and what the capabilities mean
Countries organise their numbers differently, so virtual numbers come in kinds:
- Local numbers belong to a city or region and read as a fixed line there. Good for a business presence or for looking settled in a place.
- Mobile numbers are not tied to a region and read as personal. Good for anything where people expect to text a mobile.
Each number also has capabilities: Calls, SMS and sometimes MMS. Not every number in every country supports all three, which is why Second Phone shows the capabilities when you choose a country and a number. A voice-only number cannot receive texts; an SMS-only number cannot take calls.
What a virtual number depends on
Connectivity. Because calls travel over the internet, the app needs data or Wi-Fi. A number does not depend on any particular SIM, which is why it works abroad, but it does depend on being online.
An active account. Numbers are rented, not owned outright: a subscription covers your first number, and coins cover extra numbers for a chosen term. When a term ends and is not renewed, the number expires and is eventually released back to the pool for someone else.
Rules of the country. Some countries require a registered address before a number goes live. Where that applies, the app asks for it.
What a virtual number cannot do
It cannot make you anonymous: you sign up with an identity and misuse is still misuse. It cannot guarantee that every service accepts it, because some check number ranges. It cannot ring without a connection. And a virtual number is not a data plan: it carries calls and texts, not your internet.
Why people use them
Everything else on this blog is a specific answer to that question: a number for work, for privacy, for another country, for a temporary need. The common thread is control. A virtual number can be named, scheduled, forwarded, recorded, paused and retired, none of which a SIM-based number allows. See Get your first number for the practical start.
Frequently asked questions
Is a virtual number the same as VoIP?
VoIP is the underlying technology, voice carried over the internet. A virtual number is a phone number delivered that way. All virtual-number apps use VoIP for the call itself.
Can I keep a virtual number for years?
Yes, as long as it is renewed. Many people hold one for years as a permanent second number. Auto-renew keeps it from lapsing.
Why can't I make a call sometimes?
Usually one of four things: no connection, an expired or deactivated number, no subscription or coins to pay for the call, or a number that does not support calls. The guide I can't make or receive calls walks through them.