Apple Confirms iPhone 18 Pro Max Cellular Issue, Affected Devices Need Replacement

Apple has confirmed a cellular connectivity problem affecting a small number of iPhone 18 Pro Max users on AT&T, and some customers whose phones have already lost cellular service may need to have their devices replaced.

The issue can cause an affected iPhone 18 Pro Max to lose its connection to AT&T's network, preventing phone calls, text messages and cellular data from working. In some cases, the iPhone displays “SOS” instead of a cellular connection. Apple says software updates can help prevent the problem, but they cannot restore service on devices that have already experienced the failure.

Apple Confirms the iPhone 18 Pro Max Problem

After reports from affected customers began appearing shortly after the iPhone 18 Pro Max launched, Apple has now acknowledged the issue. Apple says it has identified a problem affecting a small number of iPhone 18 Pro Max devices connected to AT&T. The company released iOS 27.0.1 and an AT&T carrier settings update designed to help prevent additional devices from being affected.

However, there is an important distinction for customers who are already experiencing the problem. If an iPhone 18 Pro Max has already lost cellular service because of this issue, Apple says installing the latest software will not reactivate the device. Instead, the affected iPhone needs to be replaced.

Which iPhone 18 Pro Max Models Are Affected?

So far, Apple says the problem has only been observed on iPhone 18 Pro Max devices using AT&T in the United States. Apple has not reported the same problem affecting other iPhone models or other carriers. The issue also appears to be limited to the U.S. version of the iPhone 18 Pro Max.

The U.S. iPhone 18 Pro Max uses Qualcomm's Snapdragon X80 modem, while iPhone 18 Pro Max models sold in other countries use Apple's custom C2 modem. It remains unclear whether the modem difference is related to the AT&T problem. Apple and AT&T have not publicly explained the underlying cause of the failure.

What Happens When the Problem Occurs?

Affected users may suddenly find that their iPhone cannot connect to AT&T's cellular network.

That means essential services such as:

Phone calls
Text messages
Cellular data
Emergency calls

may be affected.

AT&T previously warned customers that some affected phones could be unable to complete calls, texts or data connections, including calls to 911. The carrier advised iPhone 18 Pro Max owners to install the latest software. Reports from customers indicate that affected devices can remain in SOS mode, leaving users without normal cellular connectivity.

Apple Says to Install iOS 27.0.1

For iPhone 18 Pro Max owners who have not experienced the cellular failure, Apple strongly recommends installing iOS 27.0.1.

To check for the update:

Open Settings.
Tap General.
Select Software Update.
Install iOS 27.0.1 if it is available.

Apple has also released an AT&T carrier settings update. AT&T users can check for it by opening Settings > General > About. If the update is available, the iPhone should prompt the user to install it.

Apple says the carrier update is intended to prevent the problem from occurring, rather than repair devices that have already lost cellular service.

Already Lost Service? You May Need a Replacement

This is the most significant part of Apple's announcement. If an iPhone 18 Pro Max has already been affected and lost cellular service because of the AT&T issue, Apple says the device cannot be restored through a software update.

Affected customers should contact Apple Support or AT&T, or visit an Apple Store or AT&T location to arrange assistance and a replacement. The fact that Apple is requiring hardware replacement suggests the problem may involve a hardware-level failure, although Apple has not confirmed the exact cause.

Apple and AT&T Still Haven't Explained the Cause

Despite confirming the problem, Apple and AT&T have not yet provided a detailed explanation of what causes the iPhone 18 Pro Max to lose cellular service. MacRumors reported on October 5 that both companies still had not disclosed the underlying cause. Apple has also not confirmed whether a dedicated service program will eventually be created for affected devices.

That leaves some important questions unanswered, including why the problem appears to affect the iPhone 18 Pro Max on AT&T and whether the modem hardware plays a role.

What iPhone 18 Pro Max Owners Should Do

If you own an iPhone 18 Pro Max and use AT&T, the safest step is to install iOS 27.0.1 and make sure your carrier settings are up to date. If your phone is working normally, the updates are intended to reduce the chance of experiencing the problem.

If your iPhone has already entered SOS mode and cannot connect to AT&T despite troubleshooting and updating, Apple says a software update will not restore service. In that situation, contact Apple or AT&T about a replacement.

For now, the issue appears to be limited to a relatively small number of devices, but the reports have generated significant concern among iPhone 18 Pro Max owners.

The Bottom Line

The iPhone 18 Pro Max remains one of Apple's most advanced smartphones, but the AT&T cellular issue is an important problem for affected customers. Apple's current solution is straightforward: update your iPhone to prevent the issue, but replace the device if it has already suffered the cellular failure.

Apple has not yet revealed exactly what causes the problem, so additional information or a more formal repair program could emerge as the investigation continues.