iphone 6 doesn't ring or vibrate

Last week I wrote this question:

"My iPhone 6 does not ring if the person calling me makes the call through Siri. If the call is made by first hitting contacts or typing in the number, my phone will ring. But if the person uses Siri to call me, it goes straight to my voicemail. All updates have been made (using 9.1) and I see nothing wrong with the settings that might be causing this."

Then for a few days my phone did seem to work properly. Now it is not ringing on calls or vibrating on texts no matter if they come from Siri or are hand dialed. Sometimes calls go straight to voicemail. Sometimes the call appears to go through, but I hear no sounds. The "Do Not Disturb" feature is not turned on so I don't think that is the problem. Any ideas for me?