My iPhone doesn't always ring, why?

I just had this problem, turns out I had set the 'Do Not Disturb' to manual only receiving calls from favourites and when the screen is on.

Me too, just figured it out! hahahah

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

Fixed in a sec: http://www.payetteforward.com/my-iphone-wont-ring-heres-the-real-reason-why/

Thank you for this simple solution. I don't know how my "do not disturb" got turned on, but this was my problem!

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.

Are you sure that it isn't just in your pocket and you are in a somewhat noisy situation causing you not to hear it?

I had thought that about my iPhone 4S as well, just like several other phones, but when it was sitting out or in a belt clip, I never missed a call and it never "didn't ring". When I believed it didn't ring, it was because it was in my jeans pocket. I absolutely *HATE* belt clips & cases. When the day comes that a decent cell phone won't fit in my front jeans pocket where I can still move around comfortably and normally, I just won't have one. Anyway, when I started setting my phone down near me (as a test, it was inconvenient), I always heard it ring. The very next day, in my pocket, I missed calls because I couldn't hear it again.

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.

While many of the responses to this question point to the iPhone as the problem, the real problem may be the provider you use does not having sufficient RF channels to service your location at the time your missed call comes in. Cell towers have a number of channels which are licensed to your carrier by the FCC that they use to communicate with your phone. If the tower is loaded with other calls at the time someone is trying to reach you, the provider may try and reach you though the next closest tower which may or may not be able to "see" your phone. If they are out of local channels and can not see you from the next closest one, the call would go to voice mail. Your provider would then use a data or control channel in your area to report the missed call or report a voice mail if one was left. This tower loading issue can occur just like in the old days when you would try to make a long distance call and get an "all circuits busy" message. Nothing different, there is only so much capacity available and when its all in use your calls will go to voicemail. Ask your provider what the loading is on the tower in your area and that could be the problem and your phone will be free from blame... Sometimes that provider with the most coverage and the most customers also has the most dropped calls due to overloading of their system with voice and data traffic...

Don't know how it got set but the Do Not Disturb setting somehow got enabled. Disabling it fixed the issue. Thank for the tip!!!

Fixed mine too! Thank you so much!!

Jack did you find a solution? I know your post is old. I have an iPhone 6, and having the same problem. Thank you

Thank you so much didn't even know that little switch was there. Wow. Just switched from Galaxy s 5 to iPhone 5. It's ok so far but definitely totally different. Going to take some getting used to!!