I have an on going problem with not receiving incoming calls.  While I am active on the phone, the phone will ring perfectly  but if I let the phone sleep for a few minutes the phone shuts the app down.  I have enabled all power settings to keep it alive along with push witin the app.  In the phone I selected the battery setting to never shut down the app and still it doesn't work.  I am using a huawei nova plus and I believe it has Android 7 installed.  Some help would be much appreciated!