According to messages posted on the Apple Support Communities forum from owners of new phones from
Communication issues on iPhone 12
As we said, it happens like in networks4G LTE and 5G networks, and turning on and then turning off airplane mode returns the connection, that is, it solves the problem. Others say they need to restart their phone or remove and replace the SIM card in order for the phone to sync with their carrier's network.
Here's what joxesCA writes on the Apple Community Forum:
Received my iPhone 12 Pro on Friday.I activated it on Saturday. On Sunday I drove for 10 minutes and when I arrived at my destination I saw no reception lanes or service. And in the center of the screen in a gray box: your iPhone is not activated. The only way to restore the connection — Switch airplane mode to ON and then OFF. The iPhone had 5G Auto cellular mode. I switched it to LTE for testing. And it was the same. So I reset my network settings: same problem, and I reset the iPhone as a new iPhone and reinstalled everything from scratch (not from a saved backup): same problem. I found the exact location where the phone lost network. If the phone loses network, it means that I have reached the end of the coverage area of a certain antenna. It looks like something happened to the phone. I called my operator and they told me everything was fine on their end and I had the correct SIM card for the 5G device … I never had this problem with 11 pro."
Users of the iPhone 12 line also unsubscribedon Reddit to explain what's going on with them. One participant wrote: “It's almost like a clock to me. If you actively use your phone for more than 20 minutes at a time, you are bound to experience signal loss. I've tried endless workarounds to no avail. The only real workaround is that when this happens, there's really no choice but to put the phone down and wait at least a couple of minutes for it to restore the signal and connection.
One Australian iPhone 12 Pro owner wrote:“I have the same problem with Vodafone in Australia. After upgrading from iPhone 11 pro to iPhone 12 pro. My new phone just sometimes completely loses connection, and in some cases it just shows 3G. I haven't seen 3G in years, but now I switch to 3G most often — or I don’t use the services at all. The only common solution that works to restore service is — This is rebooting the phone."
Four iPhone 12 usersfaced other problems. Last month, it was discovered that the display on some devices glowed green and gray. Interestingly, Apple advised technicians not to service devices with this problem and insisted that they tell iPhone owners to just keep updating their phones in a timely manner. This definitely suggests that a software update is on the way; It is hoped that anything that bothers these devices due to loss of connection can also be fixed with a software update.