iPhone 18 Pro Max loses AT&T service; Apple recommends device replacement

Owners of iPhone 18 Pro Max devices on US carrier AT&T are reporting a complete loss of cellular service. Apple has confirmed the fault and recommends replacing the phone if the failure has already occurred.

The device switches to SOS mode, preventing calls, text messages and mobile-data use. AT&T says that, in some cases, even emergency calls may fail.

Updates are meant to prevent failure

Apple recommends installing iOS 27.0.1, while AT&T is distributing a carrier-settings update. It should appear automatically on phones within 14 days; users can check manually under Settings → General → About.

Apple says the two updates should prevent the known fault. If service has already been lost because of it, the updates will not restore connectivity, and the company advises contacting Apple or AT&T to replace the device.

Owners report unsuccessful fixes

Reddit users describe repeated eSIM replacements, network-settings resets and store visits that did not restore service. Some owners say the problem was resolved only after the smartphone was replaced.

Apple told MacRumors and 9to5Mac that the fault affects a “small number” of users. The company has not disclosed the exact number of affected devices or explained the technical cause.

So far, the reports concern iPhone 18 Pro Max devices operating on AT&T in the United States. There is no information about similar cases in Europe or other regions outside the US.