[expertentipp]

> calling-over-wifi is less trackable than using a tower.

Not if using whatsapp/messenger for calling over wifi and the probability that the other person has an app capable of calling over wifi different than whatsapp/messenger is rather low.

[blisterpeanuts]

My Samsung with T-Mobile is capable of connecting to cellular networks via wifi, which is useful in my neighborhood where T-mo is a weaker signal.