Apple has confirmed the cellular problem affecting some iPhone 18 Pro Max devices on AT&T, revealing that phones which have already lost service cannot be fixed with a software update and will need to be replaced.
The confirmation marks a significant development in an issue The Apple Post has been following since shortly after the iPhone 18 Pro Max launched, with affected customers reporting devices dropping into SOS mode and losing access to calls, messages, and cellular data.
In a statement provided to 9to5Mac, Apple said it has identified an issue affecting a “small number” of iPhone 18 Pro Max users on AT&T that can cause the device to lose service and become unable to make calls.
Apple released iOS 27.0.1 earlier this week and is now issuing a separate carrier settings update. Together, the updates are intended to prevent the problem from occurring on iPhone 18 Pro Max devices that have not yet been affected.
However, the updates cannot restore cellular service once an affected device has already lost it.
Apple says iPhone 18 Pro Max devices that have already experienced the failure require a hardware replacement. Customers in that situation should contact Apple Support or AT&T, or visit an Apple Store or AT&T location.
That distinction explains why some customers continued to report problems after installing iOS 27.0.1. The Apple Post reported earlier today that AT&T was urging all iPhone 18 Pro Max customers to install the update immediately, even as some already-affected users said it hadn’t restored their cellular connection.
AT&T’s warning said the issue could leave some phones unable to complete calls, texts, or data connections, including calls to 911.
Apple’s new explanation clarifies that iOS 27.0.1 was never intended to repair a device after the cellular failure had already occurred. Instead, the software update and new carrier settings are designed to stop unaffected devices from developing the problem.
The new carrier settings update will install automatically over the next 14 days. Customers can attempt to trigger it immediately by opening Settings, selecting General, and then About.
The Apple Post first reported the AT&T connectivity and eSIM complaints last week, when customers described repeated SOS mode, failed eSIM troubleshooting, and unreliable cellular service.
At that stage, neither Apple nor AT&T had established publicly whether the problem was caused by software, carrier provisioning, or hardware.
The U.S. version of iPhone 18 Pro Max is the only model in Apple’s latest iPhone lineup to use a Qualcomm cellular modem. iPhone 18 Pro and iPhone Duo use Apple’s C2 modem worldwide, while iPhone 18 Pro Max models sold outside the United States also use Apple’s modem.
Apple has not identified the modem as the cause of the problem, and there is currently no evidence establishing that the Qualcomm hardware itself is responsible.
For AT&T customers whose iPhone 18 Pro Max is still working normally, Apple’s guidance is to install iOS 27.0.1 and the carrier settings update. Customers whose device has already lost cellular service should seek a replacement rather than relying on those updates to restore connectivity.