Up to Android 7.1 it was possible to end an incoming call by using the ITelephony.endCall()
method and giving your app the permissions
Please check below 2 link which is helpful to you:
Permission is only granted to system app, in Manifest
https://source.android.com/devices/tech/config/perms-whitelist
above link is used for white-list your MODIFY_PHONE_STATE permission. This is for security purpose so if you want to access this kind of permission at that time to white-list your permission after you will call your operations.
I think as per android oreo latest update you can receive phone call in your activity using inbuilt method implementation but those are not providing developer to handle end of call. Also get(read) phone number of receiving call but you need to define permission of it. I think my above description is enough to understand
Hope you understand and closed this question.