Some iPhone 18 Pro Max owners on AT&T cannot make calls, send texts, or use mobile data. AT&T has responded by sending affected customers a text message directing them to install iOS 27.0.1 immediately through Settings > General > Software Update.
The carrier’s warning is urgent. Whether the update actually resolves the problem is less certain.
What AT&T Is Telling You
AT&T alerted customers that “some phones may be unable to complete calls/text/data, including to 911,” according to reporting by MacRumors, which reproduced the carrier’s customer alert. AT&T pointed to iOS 27.0.1 as the fix and directed customers with questions to contact both AT&T and Apple.
The carrier did not explain whether the update contains a modem fix, a carrier-settings change, or another correction. Here is what the available reporting confirms:
- Reported symptoms: failed or intermittent calls, texts, and mobile data, with devices commonly entering SOS mode
- The problem affects a subset of iPhone 18 Pro Max customers on AT&T, not every user on the carrier
- AT&T’s instruction: install iOS 27.0.1 via Settings > General > Software Update
- If problems persist after updating, contact both AT&T and Apple
Because AT&T’s warning specifically includes calls to 911, do not rely on this phone for emergencies until you have confirmed that calls connect reliably. Keep another phone available in the meantime.
What Apple Has Actually Confirmed
Apple’s published iOS 27.0.1 documentation covers one documented iPhone 18 Pro Max problem: an unexpected restart when Face ID fails to authenticate. The notes do not mention AT&T connectivity, failed calls, SOS mode, or eSIM provisioning, according to Apple’s support page.
Apple has not publicly confirmed that iOS 27.0.1 resolves the AT&T cellular problem. The U.S. iPhone 18 Pro Max reportedly uses a Qualcomm cellular modem, a detail that may be relevant, but available reporting does not establish the modem as the confirmed cause of the failures.
Mixed Results From Users
Reports from MacRumors Forums, Reddit, and Apple’s Support Community indicate that some customers continued experiencing failures after installing the update. That means iOS 27.0.1 cannot yet be described as a confirmed universal solution.
One reported case, cited by AppleInsider, involved Apple testing an affected device, finding no apparent fault, and replacing the unit; the replacement reportedly restored connectivity. That is an individual account, not a validated general solution.
What to Do Right Now
Because AT&T’s warning includes the possibility of being unable to reach 911, keep a separate phone available for emergencies until you have confirmed that calls connect reliably. Do not test emergency calling by placing an unnecessary 911 call.
Install iOS 27.0.1 if it is available on your device. AT&T specifically recommends it, and the update addresses at least one documented iPhone 18 Pro Max issue.
After installing, actively test outgoing calls, incoming calls, SMS, mobile data, and network registration. Do not assume installation alone means the cellular problem is resolved.
If your phone remains in SOS mode or connectivity stays unreliable, contact both AT&T and Apple. The underlying issue may possibly involve account-level settings or eSIM provisioning, and either party may need to investigate on their end.
A lasting resolution may possibly require a subsequent iOS release, a carrier-settings update, AT&T network-side corrections, eSIM reprovisioning, or device replacement. None of those options has been confirmed. Watch for further updates from both AT&T and Apple as the situation develops.
