ZDNET’s key takeaways
- Some iPhone 18 Pro Max users on AT&T are losing cellular service.
- Apple said two updates could help prevent the problem.
- Affected phones require a free hardware replacement.
If your iPhone 18 Pro Max has lost service on AT&T and is unable to make calls, send texts or even use mobile data, two new software updates are not enough to get it working again. But Apple will replace the phone for free.
A few weeks ago, iPhone 18 Pro Max owners on AT&T started reporting losing cellular service. AT&T initially urged customers to install iOS 27.0.1 “immediately,” warning the problem could prevent calls to 911.
Also: iOS 27.0.1: Apple fixes annoying iPhone 18 Pro restart issues
Apple has now confirmed to ZDNET that an issue affecting “a small number of iPhone 18 Pro Max users” on the AT&T network may cause their devices to lose service. “We released iOS 27.0.1 earlier this week and strongly encourage all iPhone 18 Pro Max users to update now, and are also issuing a carrier settings update today,” Apple said. “These updates together should help prevent this issue from occurring.”
Since the updates are intended to prevent the issue, they do not fix already affected devices. Those require a replacement, according to Apple.
What happen?
iPhone 18 Pro Max owners on Reddit have reported randomly losing their connection to AT&T, with phones switching to SOS mode. While Wi-Fi still works, they can’t make calls, send texts, or use data over the network.
Also: 7 iOS 27 features that make old iPhones exciting again
AT&T subsequently sent a text to customers warning them about an “important Apple software update” available for affected phones. “Some phones may not be able to block calls/text/data, even to 911,” the cell phone carrier said. “Update to iOS 27.0.1 directly – Settings > General > Software Update.”
Apple did not provide an exact number of affected devices, although it only observed the issue among iPhone 18 Pro Max users on AT&T.
What is causing the AT&T issue?
Apple and AT&T have not publicly explained the cause, but the iPhone 18 Pro Max’s cellular hardware could be a factor. Our sister site, CNET, noted a recent iFixit teardown shows that the US version of the phone uses Qualcomm’s Snapdragon X80 modem.
Also: Your iPhone just got a hidden anti-scam upgrade in iOS 27
However, CNET also cites a TechInsights teardown that shows the iPhone 17 Pro and Pro Max will use the same modem, while the iPhone 18 Pro Max appears to add a new millimeter-wave antenna. Neither Apple nor AT&T has linked this antenna to the service failure.
For now, the cause remains unconfirmed.
What Apple and AT&T say to do
According to Apple, two new updates for iPhone 18 Pro Max users on AT&T are intended to prevent the mobile connection problem, but they do not restore service to phones that are already affected.
1. Install the iOS 27.0.1 Software update
If you have an iPhone 18 Pro Max on AT&T, Apple strongly recommends installing iOS 27.0.1. To check for the update, go to Settings > General > Software Update. AT&T is also urging customers to install the update.
2. Install the carrier settings update
Next, install a new firmware update on your iPhone 18 Pro Max. It will be automatically downloaded for AT&T users over the next 14 days, according to Apple. To turn it off manually, go to Settings > General > About.
What if you have already lost service?
If your iPhone 18 Pro Max is already without AT&T cellular service due to this issue, it cannot be reactivated through software updates and will require a hardware replacement instead, Apple said. The company confirmed to ZDNET that replacements will be provided free of charge.
Also: 5 iOS 27 upgrades that make a big difference — and why I love them
So, affected owners can:
- Contact Apple Support or AT&T.
- Visit an Apple Store or an AT&T location.
If you contact support, explain that you have an iPhone 18 Pro Max on AT&T that has lost service, and mention whether you have installed iOS 27.0.1 and the carrier settings update. From there request your free replacement.
AT&T previously told ZDNET that customers experiencing continued problems should seek additional support from Apple or an AT&T store. “Our top priority is that customers can stay connected when they need it most, and we’re working with Apple to make it right,” AT&T said.
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