My iPhone doesn't always ring, why?

These issues can be caused by applications like TRUECALLER the app isn't perfect and can set about blocking loads of numbers it shouldn't. Happened with me. Delete it and then go into the phone section of settings to see what's been blocked and unblock them if need be

I Have this problem too and my do not disturb is not turned on. I tried changing all sorts of settings Including have AT&T deactivate voice over lte on my account. iPhone 6 on AT&T. Oddly enough it only happens while I am at work. It did not happen when I had my iPhone 4s though. Strange. I tested it over 90 minutes yesterday by continually calling my phone from work. I'd say 80-90% of the time I would get two rings than voicemail. My cell never rang and never showed a missed call. A voicemail notification showed Up instead.

AT&T called me today to check on the situation. Call came through. He tested two more times. The last call did not come through. I noticed the first two times, my phone was not in its usual place. So I ran a test myself. I had my phone in its usual spot. Called three times with the phone in sleep mode. Only the third call actually came thru and not to voicemail. I tried a 4th time with the phone not in sleep mode and it still rang twice and went to voicemail I moved my phone to the other side of my desk and tried again. First three calls all came through. I was so excited so I tried a 4th. That one went to voicemail. I then tried with the phone not in sleep, call came through. For fun I tried one more time in sleep mode, call went to voicemail. So results: left side of desk, 3 out of 4 calls went to voicemail. On the right side, 2 out of 6 went to voicemail.

SO if you add that all up, it worked 50% of the time, but odds were better just llike 3 feet over more. Weird.

sorry this came thru in two different fonts. I copied and pasted from an email I sent. Lol.

I still think there's a problem with my iPhone 4s not ringing for every call that's not due to DND or any other setting.

HOWEVER. I did just get a call that I couldn't get to in time. At least 10 minutes later I received a voicemail message notice. It seemed like the person called and I didn't get the notice or ring, BUT actually I did get the call, it just took an electronic lifetime for the voicemail message notice to get to me. :-)

It's not the answer to all of the occurrences, because many I have the phone sitting right next to me all night only to see a message later that I missed a call.

I Had a voicemail from my sons school nurse arrive 7 hours later!!!! That was not good. Turns out it was AT&T and not Apple. they did something to my settings and the problem hasn't occurred since. Of course, it took several calls to find someone who did the right thing. My issue of the phone not ringing and going straight to voicemail was an LTE issue. Again, AT&T. Only happened when I was at work. The fix was to turn off LTE for voice and data and keep my phone on 4G at all times.

Positive. When it happened, the phone would only show a missed voicemail, but no missed call. Also, I had my phone on my desk in front of me. I could pick up my work landline and call my cellphone and watch the phone never ring. My issue was LTE. My work is like a black hole and with LTE on (even just for data) the phone wouldn't switch over to 4G fast enough to receive the call. It's the building I am in. This issue only occurred for me while I was at work. Not sure about the others though.

Nothing you can do other than trying to place the phone in an area with strong cell coverage. I've had this happen with my AT&T 3GS and my Verizon 4S.

Apple is NOT here.

This is a user to user forum.

Allan

This is not the appropriate place for that.

Allan

Did you try turning 3G off?

I'm off to the genius bar...wish me luck! Didn't mention I did a complete restore this morning too....

Ranting