iPhone does not ring when I get some calls--vibrates ONCE goes to VM
Occasionally, I feel the vibration go on once, but doesn't ring-- on an incoming call. And then caller is bumped right to Voice mail. I don't want that to happen but it does.
I do NOT have do not disturb on; the ringer is turned up at least 1/4-1/2way. BUT this happens.
In Settings/Do not disturb, DND is OFF; scheduled is OFF; but under SILENCE there are only two choices: ALWAYS and While iPhone is locked. While locked has a check next to it; I CANNOT get rid of that check.
I missed another important call this morning due to this... Can someone explain this and tell me what to do? Thanks in advance.
iPhone 8 Plus, iOS 13