Owners of the iPhone 18 Pro Max on AT&T have discovered a novel way to lose cellular service: just own one. According to Apple, an issue affecting "a small number of iPhone 18 Pro Max users" on AT&T's network can cause devices to lose service entirely - no calls, no texts, no mobile data. Wi-Fi still works, which is cold comfort when you're trying to call 911.

AT&T initially told customers to install iOS 27.0.1 "immediately," warning that the problem could prevent calls to emergency services. Apple then released iOS 27.0.1 earlier this week and, in a statement to ZDNET, said it "strongly encourages" all iPhone 18 Pro Max users to update now, alongside a carrier settings update issued the same day. Together, Apple says, these updates are "meant to help prevent this issue from occurring."

Note the word "prevent." If your phone has already gone full SOS mode, the software updates won't bring it back. Apple confirmed to ZDNET that affected devices require a hardware replacement - and that replacements will be provided free of charge. So if you're one of the unlucky few, congratulations: you've won a brand-new phone by losing the ability to use your old one.

Reddit users have reported randomly losing their AT&T connection, with phones flipping into SOS mode while Wi-Fi soldiered on. AT&T followed up with a text to customers warning of an "important Apple Software update" and repeating the grim caveat: "Some phones may be unable to complete calls/text/data, including to 911. Update to iOS 27.0.1 immediately - Settings > General > Software Update."

Apple hasn't said exactly how many devices are affected, only that it has observed the issue solely among iPhone 18 Pro Max users on AT&T. Neither company has publicly explained the cause, though the phone's cellular hardware is a natural suspect. CNET noted a recent iFixit teardown showing the US version uses Qualcomm's Snapdragon X80 modem. But CNET also cited a TechInsights teardown showing the iPhone 17 Pro and Pro Max use the same modem, while the iPhone 18 Pro Max appears to add a new millimeter-wave antenna. Neither Apple nor AT&T has linked that antenna to the failures, because that would be too easy.

If you have an iPhone 18 Pro Max on AT&T, Apple strongly recommends installing iOS 27.0.1 via Settings > General > Software Update. Then install the new carrier settings update, which will automatically download for AT&T users over the next 14 days - or you can manually trigger it via Settings > General > About.

If your phone has already lost AT&T cellular service because of this issue, no software update will resurrect it. Apple told ZDNET that a hardware replacement is required and will be free. When contacting support, explain that you have an iPhone 18 Pro Max on AT&T that lost service, mention whether you installed iOS 27.0.1 and the carrier settings update, and request your free replacement.

AT&T previously told ZDNET that customers still experiencing problems should seek additional support from Apple or an AT&T store. "Our top priority is ensuring customers can stay connected when they need it most, and we are working with Apple to make it right," the carrier said - a sentence that reads considerably better if you don't think about the 911 part.