Some iPhone 18 Pro Max users are reporting cellular connectivity problems, including phones switching to SOS mode, failed calls and text messages, and issues with mobile data and audio.
US telecom giant AT&T has acknowledged that some iPhone 18 Pro Max devices are experiencing cellular problems and has urged affected customers to update their phones immediately.
In a message sent to customers this week, AT&T warned that some devices may be unable to complete calls, texts or data connections, including emergency 911 calls.
How to fix the iPhone 18 Pro Max connectivity issue
AT&T is advising affected iPhone 18 Pro Max users to install Apple’s latest software update, iOS 27.0.1.
Users can check for the update by going to:
Settings > General > Software Update
However, reports from users suggest that the update has not resolved the problem for everyone.
The cellular issue had already been discussed for more than a week on Reddit and Apple’s Support Community, with users reporting problems ranging from SOS mode and failed calls to broader connectivity issues.
iOS 27.0.1 release notes raise questions
Apple’s official release notes for iOS 27.0.1 do not specifically mention a fix for cellular connectivity.
Instead, the update lists fixes for issues including a Face ID bug, a camera colour artefact and a touchscreen that could become unresponsive.
This has led some users to question whether the update is actually addressing the underlying cellular problem acknowledged by AT&T.
Different modem configurations add uncertainty
The situation has also drawn attention to the different modem hardware used in various iPhone 18 models and markets.
According to the report, the US version of the iPhone 18 Pro Max uses a Qualcomm cellular modem, while other models and international variants use Apple’s C2 modem.
It remains unclear whether the modem configuration is connected to the reported connectivity problems.
Apple has not publicly explained the cause of the issue.
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Some users report replacements fixed the problem
Some affected customers who visited Apple Stores were reportedly offered replacement devices.
Several users said their connectivity problems disappeared after receiving replacement phones, although it remains unclear why the replacements resolved the issue.
The reports have raised the possibility that the problem could involve either software or hardware.
If the issue is caused by software, Apple may need to release another update, potentially iOS 27.0.2, to address the underlying problem.
A hardware-related fault, however, would present a more significant challenge because it could require affected devices to be repaired or replaced.
For now, Apple has not publicly confirmed the root cause of the reported cellular problems or provided a detailed explanation of why some iPhone 18 Pro Max users are experiencing the issue.
