Apple confirmed that a 'small number' of iPhone 18 Pro Max users on AT&T experience cellular service disruptions, including inability to make calls, send texts, or access data. The issue, reported across multiple platforms, causes devices to enter 'SOS' mode. Apple stated that affected devices cannot regain service via software updates and must be replaced, advising users to contact Apple Support or AT&T.
To mitigate the problem, Apple released iOS 27.0.1 and an AT&T carrier settings update (version 72.1). However, users already affected report the updates do not resolve existing issues. The carrier settings update is automatically downloaded over 14 days but can be manually triggered via Settings > General > About. AT&T emphasized users should update immediately, though the fix's effectiveness remains unclear.
The U.S. iPhone 18 Pro Max is the only model using Qualcomm's Snapdragon X80 modem, while other regions use Apple's C2 modem. It is unknown if the modem difference contributes to the issue. Apple and AT&T have not disclosed the underlying cause, and it remains unclear if a hardware repair program will be initiated. Affected users are advised to seek replacements at Apple or AT&T stores.