AT&T has acknowledged that some iPhone 18 Pro Max devices on its network are experiencing cellular issues, sending a text message to customers today. The message advises an immediate update to iOS 27.0.1, stating that some phones may be unable to complete calls, texts, or data, including to 911. However, many affected users have reported that this update does not resolve the problems. Thousands of users have reported issues across various online communities like Apple Support, Reddit, and MacRumors Forums. Apple's release notes for iOS 27.0.1 did not mention any fix for AT&T cellular issues, only a Face ID fix on iPhone 18 Pro models. Last week, it was reported that affected users are unable to connect to the AT&T network for calls, texts, or data, with devices often entering SOS mode. The underlying cause remains unconfirmed, and Apple has not yet publicly commented. The U.S. iPhone 18 Pro Max uniquely uses a Qualcomm cellular modem, unlike other iPhone 18 models and international 18 Pro Max versions which use Apple's C2 modem, though it's unclear if this is a factor. If a software issue, another update like iOS 27.0.2 might be needed; a hardware issue would pose a larger problem. Further updates will be provided as new information becomes available.