Source: Apple
If your new iPhone 14 shows a pop-up message saying "SIM not supported," you're not alone. Apple has acknowledged this bug is affecting some users. When this pop-up message shows up, your iPhone might entirely freeze. According to the company, it is "investigating" the issue, and it's not a hardware problem. It reminds customers to keep their software up to date.
Apple says if you encounter the problem, wait a few minutes to see if the message disappears. If it doesn't, you shouldn't attempt to restore your device. Instead, head to an Apple Store or an authorized service provider to ask for help.