Apple’s newest flagship smartphone is leaving some United States customers unable to make calls, send text messages, or use mobile data while connected to AT&T. The issue, which forces devices into SOS mode, has prompted an urgent text warning from the carrier instructing users to install a software update.
AT&T Sends Urgent Warning After iPhone 18 Pro Max Users Lose Service
Buyers across online support communities, Reddit, and message boards describe brand-new hardware that refuses to connect to the cellular network for daily tasks or eSIM provisioning. A growing number of Apple customers who recently purchased the company’s latest flagship devices are finding themselves without reliable mobile service.
While Wi-Fi continues to function normally for internet browsing, traditional voice calls fail completely. For many affected buyers, the problem leaves devices stuck in SOS mode. Support communities are tracking at least thousands of users experiencing similar disruptions.
Carrier store employees appear largely unaware of the underlying glitch.
One forum user described their immediate frustration after picking up a device at launch:
“I got my iPhone 18 on Friday. I have coverage through AT&T. I have been noticing that I have been getting SOS on my phone. WiFi works for the internet, but I can’t make calls. Even if it doesn’t say SOS, trying to make a phone call is impossible now. I have tried everything. I went to AT&T, and they know nothing about it.
Anonymous Customer, via The Mac Observer
AT&T Urges Immediate Update While Apple Release Notes Omit Any Fix
In response to the mounting complaints, AT&T sent automated text messages to customers warning that affected phones might be unable to complete calls, text messages, or data transmissions. The carrier’s message explicitly warned that the network failures could prevent emergency calls to 911.
The text message instructed users to update to iOS 27.0.1 immediately. However, official release notes published by Apple for that software package made no mention of any network fix for AT&T customers. Instead, Apple stated that the update addressed a separate Face ID restart bug affecting iPhone 18 Pro models.
Numerous users who followed the carrier’s instructions reported that installing the update did not restore their cellular connectivity.
Uncertainty Persists Over Qualcomm Modem Hardware and Missing Guidance
The U.S. version of the iPhone 18 Pro Max uses a Qualcomm cellular modem, setting it apart from smaller Pro models and international variants that utilize Apple’s in-house C2 modem design. Observers have pointed out this notable hardware difference in the device lineup. Despite this divergence, neither Apple nor AT&T has confirmed whether the Qualcomm chip contributes to the network drops.
With devices falling within their initial 14-day return windows, some users have sought hardware replacements through retail stores. Others have reverted to previous models, such as the iPhone 17 Pro Max, while waiting for official guidance. Support representatives continue to advise affected buyers to document their issues through official Apple and AT&T help centers while investigations persist.
Will Apple issue a public comment or a dedicated software patch to resolve the AT&T cellular failures?