VoIP: internet calls in messaging apps and beyond

VoIP (Voice over Internet Protocol) is a technology for sending voice and video over the internet. It powers calls in messaging apps (Telegram, WhatsApp, Viber, Signal), video conferences (Zoom, Meet) and office IP telephony.

VoIP: your voice in small parcels over the internet

In plain words

An ordinary phone call is like a private pipe between two houses, reserved just for you. VoIP is like sending your voice as small parcels along a shared road - the internet. Usually the parcels arrive instantly, but in a "traffic jam" (poor internet) your voice may lag or cut out.

How it works

The microphone turns your voice into a digital signal.
A codec compresses the sound and splits it into packets.
The packets travel over the internet to the other person.
The app reassembles the packets and plays the voice.
If packets get lost, quality drops - the sound "bubbles" or cuts out.

Calls and video conferences over the internet

Where you'll see it

In every messaging app, video service and office phone system. Wi-Fi calling (VoWiFi) and VoLTE use similar principles but run on the operator's network using your number.

Does it matter when buying

It is useful: free calls abroad and video chat. Quality depends on how stable your internet is, not just its speed. For important calls, Wi-Fi or stable 4G is best; during power cuts VoIP works as long as you have internet.

Myths

Myth: VoIP is always worse than a normal call. Reality: With good internet the quality is often even better.
Myth: VoIP uses lots of data. Reality: A voice call uses around a few megabytes a minute or less; video uses more.

FAQ

How much data does a call in a messaging app use?

Voice uses little; video noticeably more.

Are VoIP calls encrypted?

In Signal, WhatsApp and FaceTime, end to end; in others it depends on the service.

Can I call ordinary numbers via VoIP?

Yes, some services allow it for a fee.