Help! How to turn off sending all calls to voicemail?

[Batonic]

My phone (Android 6) started to behave strange this morning, sending all calls to voicemail right away without me setting anything for that and without logging such calls as missed. I tried to find where to turn it off but had no luck. Did anyone had a similar problem and how have you fixed it? I really need to take calls for my business so it's urgent

 

[PapaGary]

Is Do Not Disturb turned on?

 

[Batonic]

It was turned off. Actually, after visiting a cell phone booth and a long phone conversation with our cell phone provider we found there was some glitch in the system (the top menu won't show when you swipe it down as well) so we ended up with the Factory data reset which solved the problem.