WhatsApp calls on an iPhone and "data" and "minutes"

Usually carriers distinguish

• minutes: for voice calls using the standard phone app, to either other phones or landlines (which can be confusing since FaceTime calls and audio use data and not voice minutes)
• sms (which can be confusing since the the message app uses data for iMessage and SMS for MMS and SMS)
• data: for all other internet traffic generated by any app that doesn’t hand off to SMS or the phone app.

WhatsApp uses data for both messages and calls. If you are in a mobile network, any activity you do in that app counts towards your data usage. If you are logged in to a WiFi network, data will be send/received over WiFi.

Contact your carrier for details how you ar set up so you can reconcile your bill and plan with how data usage on iOS records usage.

Mobile carriers provide two basic services: mobile voice service and data transmission. Mobile voice service is provided by a wireless connection to the carriers towers, and supported by the Mobile Switched Network on the carrier side, that connects to the Public Switched Telephone Network (ie. telephone service). SMS is part of this voice standard, and allows short messages be sent over the phone network, and was very popular before the rise of smart phones and fast data connections.

Your mobile phone, whether smart or not, as chips and radios that support these frequencies, connecting voice calls and other voice services.

The mobile carrier also provides data services, which are designed to carry network traffic like the internet. You have heard of things like '3G" "4G" "LTE" "5G" which refer to these faster and faster data connections. (Confusingly, some of these encompass voice and data, but let's keep is simple and just consider these 'data' connections for now). These can use a different set of signals and radios than the voice service mentioned earlier. Smart phones support both voice and data connections, though some older phones support only voice.

So, the best way to think of this that an old-school phone call uses the phone network, which counts as 'minutes' and every other application uses the data network, and counts that in gigabytes (GB). Therefore Whatsapp, which is an app, uses data or Gigabytes, not minutes.

OK, now, lets try to not get confused: lets say you have NO APPS on your brand new phone. You give your Mom or Dad your new phone number, and they call you. That app, the one that rings when they call, is what counts as minutes. EVERYTHING ELSE on your phone, counts as data or gigabytes.

Yes, you can make a voice 'call' over Whatsapp, or Facetime, or lots of other apps. But they are using the Gigabytes to send a voicecall over the data network. They don't count against your minutes, because they are not using the voice network. Its best to think of this by app: there is one app on your smartphone that counts minutes, and that is the phone app. Everything else counts gigabytes (data).

Wifi is using a different network to support the data side of your phone: when you are on Wifi, your phone is connected to the local Wifi router, NOT the carrier data network. Therefore, because your phone is using Wifi, rather than the carrier's data network, you don't have gigabyte charges. But, because Wifi only replaces the data connection with your carrier, the voice radios in your phone DO connect to the carrier. So regular phone calls, on the phone app, continue to work, as does Whatsapp. Only Whatsapp is using Wifi now, not the carrier data.