Hello,
I'm on iOS 9 beta 3, but the issue was the same since beta 1: It's as if the phone has been forced into a Do Not Disturb mode, even though it is not, and it's not during the time scheduled for it to be in that mode. I'm unable to make phonecalls and when someone calls me, the phone doesn't ring; I just see their missed call after they hang up.
Sometimes, after restarting the phone, I'm able to call.
Thanks in advance for any help!