I know that Windows 10 Mobile in previous Beta builds shows how many rings my caller waited before hanging up. This feature doesn't work properly in the latest final release on Lumia 640 XL . It only works if the caller calls me and instantly hangs up. When I return to my call history I find the caller and one ring. If the caller gives me more than one ring, Windows doesn't tell me how rings I received before the caller hanged up.
I think you misunderstood me. Read this
My Phone: Lumia 640 XL OS: Windows 10 Mobile