AT&T Urges iPhone 18 Pro Max Owners to Update Amid Cellular Issues

AT&T has notified customers that some iPhone 18 Pro Max devices on its network are experiencing cellular failures. The carrier warned that affected phones may be unable to complete calls, send texts or use data, including for 911 calls.

The company urged users to install iOS 27.0.1 immediately through Settings > General > Software Update. Many users, however, have said that the update does not resolve the problem.

Thousands Report Network Failures

At least thousands of iPhone 18 Pro Max owners have described the issue across Apple Support Community, Reddit and the MacRumors Forums. Network access can fail continuously or intermittently, with affected devices typically entering SOS mode.

Apple Notes Do Not Cite a Fix

Apple’s release notes for iOS 27.0.1 do not mention a fix for AT&T cellular problems. The update is described as addressing a Face ID issue on iPhone 18 Pro models.

Apple has not publicly commented, and the underlying cause remains unconfirmed. If the fault is software-related, another release such as iOS 27.0.2 may be needed; a hardware problem would represent a more serious issue.

Qualcomm Modem Limited to U.S. Model

The U.S. iPhone 18 Pro Max is the only new iPhone unveiled last month that uses a Qualcomm cellular modem. The iPhone 18 Pro and iPhone Duo use Apple’s C2 modem worldwide, as does the iPhone 18 Pro Max outside the U.S.; it is unclear whether that difference contributes to the failures.