iPhone 18 Pro Max: Apple confirms cellular failure, affected devices need replacing

After mysterious popping noises recently caused problems with the iPhone 18 Pro, reports are now mounting of complete cellular connectivity loss on the iPhone 18 Pro Max when used with US carrier AT&T. Instead of a normal cellular connection, the device displays SOS mode. Calls, text messages and mobile data are unavailable. According to AT&T, even emergency calls may fail.

As Apple confirmed to MacRumors and 9to5Mac, the issue affects a “small number” of users. The company strongly recommends installing iOS 27.0.1. In addition, AT&T is rolling out a carrier settings update. It should be offered automatically within 14 days. Alternatively, users can manually check for it under Settings → General → About. Both updates are intended to prevent the known issue. However, if the problem has already occurred, Apple says the updates will not restore cellular connectivity on the affected iPhone. In that case, the device must be replaced. Affected users are advised to contact Apple or AT&T.

Apple has not yet explained what exactly is going wrong on a technical level or why the issue cannot be fixed with a software update once it occurs. The company has also not provided a specific number of affected devices. So far, however, the problem appears to be limited to iPhone 18 Pro Max models using AT&T's network in the US. There are currently no indications that the issue also occurs in Europe or other regions outside the US.

Reddit confirms: Replacement is the only fix once the issue occurs

On Reddit, much of the frustration surrounding the situation stems from the difficult support process. Affected users report repeated eSIM replacements, network resets and store visits that failed to resolve the issue. Some say they feel caught between Apple and the carrier, with each side passing responsibility back and forth. For several users, only a replacement device reportedly solved the problem, which aligns with Apple's statements. AT&T customers with an iPhone 18 Pro Max who have not yet encountered the issue should therefore install iOS 27.0.1 and the new carrier settings as soon as possible to help prevent a connectivity outage.