Phone badge not clearing calls after reviewing

I called the US Cellular "Tech2" department today and we were able to recreate the problem on his demo phone. Every iPhone tested on the US Cellular network so far appears to have this same exact issue. The tech was going to open a support issue with Apple, but said it would be up to them if they resolved it.

Thanks for your help!

Can not rule out it being a US Cellular issue, but they claim they have done everything they can on their side. AT&T does not cover this area and the Verizon coverage is limited. I only know a few people that use Verizon as their carrier, but none of those people have iPhones.

Just a little while ago I took two iPhones... One 5s and One 6s. They are both fully updated to IOS 12.1. I "Erased All Content and Settings" on both of them. I did not change any settings, or install any apps. Basically just as if I had taken them from a new box. I called both cell numbers twice and each time I called...the badge number increased by one as it should have. I then opened the "Phone" app that was displaying 2 missed calls on the badge. I then selected "recents" at the bottom of the page and left it open for 10 seconds. I then double tapped the home button and swiped up to close the "phone" app and both of the recent calls still appeared as missed calls.

We have landlines for normal business hours, but this phone is used for after hours service. Have tried "Reset All Settings" and even "Erase All Content and Reset Settings"... again our service provider has deleted the phone profile and recreated on their side. This is an issue I have contacted my phone provider at least 30 times over the last 6 years and we always come up empty handed. Originally I was always told to wait for the next IOS version, but that was probably back on version 9 at the time. Now of course Apple is probably not going to invest much effort in the 5s & 6s which I don't blame, but I can't justify buying a new iPhone if the new is going to have the same problem. Each reset we started as a new phone and did not restore from backup. Have tried 5s phones and 6s phones, and see other users complaining of same issues on rev 7 and 8. Basically, we can not get it to work on any iPhone period and have tried several. I would buy a new iPhone if it would resolve this issue, but there is no sign that a new one would resolve this.

MDM? "Mobile Device Manager"?

These are standard out of the box phones. They are all US Cellular devices which is common in this area. Same problem multiple users, neighbors, friends... all do the same thing.