callkit default UI for outgoing call

I use outgoing call only in the app on iOS 10.3.3. If I do not have connected headphones to iPhone then pressing on lock button will end the call. But what if I have connected headphones?

Sometimes (after lock) I see native UI. Sometimes I see just time counter without any buttons (like speaker, mute, etc). Is there any special flag (or I should implement some delegate?) to allow see native callkit screen after pressing lock button? It looks like I tried everything here…

P.S. I know this screen could be showed while user take a call while iphone locked. But I would like (and I got it several times at least) to get this screen on lock device.

Am I missed something?