After I did those, I also reset network settings and then also a forced reboot and so far things have been better.. This seems to be a widespread issue for those with iPhones on Verizon as this issue pops up here, MacRumors, Apple forums and elsewhere. It would be nice if a root cause can be found to prevent this from happening in the future.
I've been having this same issue since receiving my iPhone 12 Pro Max. I've spent hours on the phone with both Apple and Verizon. Apple insisted that I needed to send them my device and be without a phone for up to a week. I declined to do so because it's ridiculous to expect someone to be without a phone without a replacement device in 2020/2021. Verizon also spent a large amount of time troubleshooting, including attempting to deregister and reactivate my phone on the network. A Verizon tech told me that my phone had not properly registered when I received it, and insisted that the problem should be resolved. It worked fine for a few days and then went back to not ringing. I've found that power cycling the device fixes the problem for anywhere from a few hours to a few days. It's extremely frustrating that such an expensive device with such expensive service has such a glaring failure to delivery basic functionality and that any attempt to resolve the issue requires the investment of MANY hours of my own time, mostly spent on hold, and frequently being hung up on by Verizon personnel.
mchesler, we are disheartened to learn that you've spent so much of your time attempting to get this issue resolved as the last thing we want is for your device to not work. It is never our intentions to deliberately hang up on you as normally this can be a system issue where this can happen with large call volumes in our system at one time. To ensure we're on the same page, can you please clarify whether this is happening with all people call you, or just certain contacts or calls? Also, does this issue happen everywhere or just in a particular area?
I’m having the same issue. After numerous unsuccessful calls with Verizon and Apple, I am even more disgusted than ever. Both Apple and Verizon deny any issues.
Try resetting your network settings on your iPhone. That worked for me for months until one day it didn't. While I was on the road about 3 months ago, I text chatted with support, they resolved it on their end again. I reset the network setting like I did before, it worked for a few months. Then about a month ago, I noticed my account only reported data usage and SMS text messages, but no talk time (it said 0 for two months). Someone then tells me they can't leave a voice message. They had to fix that for their end again, and they sent me a new SIM card. So far so good. I think there may be a bug in how the network switches 5G? Who knows, for 20 years I never had ANY issues like this. All of a sudden with the first 5G iPhone I've had multiple instances of unreliable service (although it is always something to do with inbound voice calls).
I was having my calls go to VM Message Center or have them go right to VM w/o ringing. Toggling VoLTE fixed it for me. Samsung S9 Android Oreo