Internet calling FAQ: short answers

Quick answers to the questions people ask most about calling over the internet. Each answer links to a full guide with sources.

Basics

What is the difference between VoIP and a normal phone call?

VoIP sends your voice as data packets over an IP network. Today most "normal" mobile calls are VoIP too (VoLTE), but run by your operator inside its own network. The practical differences are between carrier calls and app calls: who you can reach, whether emergency calls work, and who can see the content. Full guide.

Does the person I call need the same app?

For app-to-app calls, yes. To reach an ordinary phone number from an app, you need a service that connects to the telephone network, which usually charges per minute. Carrier Wi-Fi calling reaches any number with no app at all. Compare the options.

Is Wi-Fi calling the same as WhatsApp calling?

No. Wi-Fi calling is your operator's service using your phone number over Wi-Fi; WhatsApp calls connect WhatsApp accounts. Wi-Fi calling explained.

Cost and data

How much data does a voice call use?

For a voice-only app call on a modern codec, roughly a few tens of megabytes per hour counting both directions; about 70 MB per hour for telephone-quality G.711. Video uses many times more. See the calculation.

Does Wi-Fi calling use my mobile data?

No. It uses the Wi-Fi connection. Calls are billed according to your operator's tariff.

Is roaming free in Europe?

For customers of EU/EEA operators travelling periodically within the EU, Iceland, Liechtenstein and Norway, calls, texts and data are charged at domestic prices, subject to fair-use rules. Switzerland and the UK are not covered by law. EU roaming rules.

Phones and numbers

Why does my app only ring when it is open?

Usually battery optimisation or blocked notifications. Allow notifications and exclude the app from battery restrictions. Device support guide.

Will my old phone stop working when 3G is switched off?

If it cannot make VoLTE calls on your operator's network, it may lose the ability to call. How to check.

Can I keep my number when I change provider?

In the EU and the US, yes, within the same country. In the EU the port must be completed within one working day of the agreed date. Porting and caller ID.

Do I need an eSIM?

No, but it makes adding a travel data plan or a second line easy. Your phone must support eSIM and not be locked to an operator. eSIM guide.

Safety and privacy

Can I call 112 or 911 from a calling app?

Generally not. Use the phone dialler. Carrier calls, and Wi-Fi calling on most networks, can reach emergency services. Emergency calls guide.

Are app calls private?

Apps with end-to-end encryption protect the content of calls from the provider, but not necessarily metadata or backups. Ordinary phone calls are not end-to-end encrypted. What apps encrypt.

Why does my call sound robotic?

Packet loss or jitter, most often from weak Wi-Fi or a congested upload. Troubleshooting guide.