Phone (app) and cellular data

[geta]

When my cellular data is open and im making phone calls, im getting message to turn on cellular data for the phone, its not that without this i cant make phone calls, so what the reason for it? why i "need" to have it open and let it 'eat' my data?

 

[C DM]

When does that pop-up message come up? As soon as you dial a number, or at some other point?

 

[geta]

The message coming up when im dialing a number while the cellular data is on.
Also i've noticed im getting the message as soon as im opening the phone "app"...

 

[geta]

Am i the only one encountered this problem? or nobody noticed (or maybe dont care) when they making phone calls its also using cellular data when its on?

 

[C DM]

Am i the only one encountered this problem? or nobody noticed (or maybe dont care) when they making phone calls its also using cellular data when its on?

Is data actually being used during a call?

 

[geta]

Is data actually being used during a call?

Yes.
That's why im keeping the toggle off and would like to know what it using the cellular data for.