International Calling Apps Compared: WhatsApp vs Viber vs TwinPhone

Before comparing, let's clarify something most comparison articles get wrong:

App-to-app calls (WhatsApp to WhatsApp, Viber to Viber) are free. They travel entirely over the internet. Both people need the same app installed.

App-to-phone calls (calling a real landline or mobile number) cost money. The call has to exit the internet and connect to the phone network. This is where pricing matters.

If both people have the same app, the comparison is simple — use WhatsApp or Viber, they're free. But if you need to call a landline in Japan, a mobile in Brazil, or a business phone anywhere — that's a completely different game.

WhatsApp is the world's most popular messaging app with 2+ billion users. But here's its biggest limitation for international calling:

WhatsApp cannot call regular phone numbers. Period.

WhatsApp only supports app-to-app calls. If your grandmother in Mexico has a landline, or your business contact in Germany has an office phone, WhatsApp simply can't help you.

Pros: Free app-to-app calls, end-to-end encrypted, huge user base. Cons: Cannot call real phone numbers, no virtual numbers, no call recording, requires both people to have the app.

Viber has a feature called "Viber Out" that lets you call real phone numbers for a fee. It's the closest competitor to dedicated calling services.

Rates vary widely by country, and Viber's rate pages show prices only in the browser, by the reader's location, so we do not quote them here — check each destination individually.

Pros: Can call real phone numbers, decent rates to some countries, combined messaging + calling app. Cons: Requires app download, rates inconsistent across countries, no browser option, social features clutter the interface, limited call recording.

TwinPhone is designed for one thing: calls to real phone numbers in 145+ countries.

Each country has its own per-minute rate, shown before you dial; $0.02/min is the rate to the US and Canada only. Billing is per minute, rounded up. No app to download — works in Chrome, Edge, Firefox, Brave and Safari. Every call encrypted with TLS + SRTP.

Pros: browser-based (no download), no subscription, encrypted, virtual numbers in the US and Canada, team features. Cons: Not a messaging app (by design), $10 minimum top-up, not the lowest rate to every country, requires an internet connection.

Here's what TwinPhone bills per minute to mobiles in popular destinations:

United States: WhatsApp (N/A — can't call phones), TwinPhone ($0.02). Japan: WhatsApp (N/A), TwinPhone ($0.16–$0.24). India: WhatsApp (N/A), TwinPhone ($0.08). Brazil: WhatsApp (N/A), TwinPhone ($0.06). Nigeria: WhatsApp (N/A), TwinPhone ($0.30). Germany: WhatsApp (N/A), TwinPhone ($0.22).

Viber Out figures are not in this list: its rate pages show prices only in the browser and depend on where you are, so compare them for your own destination. The pattern that does not change: WhatsApp can't compete here because it doesn't call phone numbers at all, and between paid services the cheaper one depends on the country.

Use WhatsApp for free messaging and video calls with people who also have WhatsApp.

Use Viber if you're already in the Viber ecosystem and want occasional phone calling.

Use TwinPhone if you regularly call real phone numbers internationally from a browser, with no app to install and no subscription. Check the rate to your country first: it is not the lowest everywhere.