iPhone call sound not playing on speaker or headset

The problem is that the ringtone does not sound in the iPhone speaker, but in the phone headset, although you do not use it. Or it does not sound at all, although you have correctly selected the sound and vibration in the iPhone, having made all the necessary settings.
The opposite situation can also occur, when the ringing tone sounds in the smartphone speaker, although you are using a headset or headphones.

[antonvons]

That was the problem I had and had forgotten that I had long ago set routing to "speaker". Going back to automatic was the solution. Thank you