IPhone6 rings about once an hr , or after an incoming or out going calls and texts . Screen remainsdark ! The ring is the one for reminders . I have turned off the phone and restarted . Cleared all notices ,changed ring tone and waited . Old ring tone some where around an hour came back . Same stuff . Oh , before all this happened the phone put itself in do not disturb mode . Took it out of mode , and has been ringing w ever since ! Any thoughts ?m