Apple and AT&T Have Yet to Explain Cause of iPhone 18 Pro Max Issue

In a statement shared with MacRumors on Friday, Apple said that iPhone 18 Pro Max users who have experienced an issue where AT&T cellular service does not work will need to have the device replaced, as the issue apparently cannot be fixed with a software update once it has occurred. That is a big deal, as it hints at hardware failure, but we lack details since Apple and AT&T have yet to disclose the underlying cause of the issue. A spokesperson for AT&T directed us to Apple, which has yet to respond to our latest request for comment. It is possible that Apple is still investigating the issue, but so far our follow-up questions have been met with radio silence (pun intended). In the meantime, all we know is that Apple said iOS 27.0.1 and an AT&T carrier settings update released last week "are meant to help prevent this issue from occurring," so iPhone 18 Pro Max users who have not experienced this issue should ensure that both of these updates are installed immediately to avoid potential future impacts. To install iOS 27.0.1, open the Settings app on your iPhone and tap General → Software Update. The carrier settings update for the iPhone 18 Pro Max will automatically download for AT&T users within the next 14 days, according to Apple. To manually trigger the update, users can open the Settings app and tap General → About. Apple said it has only observed this issue with iPhone 18 Pro Max users on the AT&T network. No other iPhone models or carriers are known to be impacted. Notably, U.S. models of the iPhone 18 Pro Max rely on Qualcomm's Snapdragon X80 modem for cellular connectivity, while variants of the device sold in all other countries are equipped with Apple's custom C2 modem. It is unclear if this modem difference is a factor in this AT&T issue, or if the overlap is merely a coincidence. We have reached out to Qualcomm and will share the company's response, if any. Apple said a "small number" of iPhone 18 Pro Max users experienced this AT&T issue, which prevents phone calls, text messages, and cellular data from working. A "small number" is Apple's standard wording for these types of issues. Thousands of users have complained about the issue across the Apple Support Community and other platforms. Popular StoriesApple Event Live Blog: iPhone Duo, iPhone 18 Pro, and MoreWednesday September 9, 2026 9:10 am PDT by Jordan GolsonApple's "Surprise and Shine" event kicks off today at 10:00 a.m. Pacific Time, where we're expecting to see the foldable iPhone Duo, the iPhone 18 Pro and Pro Max, Apple Watch Series 12 and Ultra 4 models, new AirPods 5 earphones, and perhaps some other announcements. Apple is providing a live video stream on its website, on YouTube, and in the company's TV app across various platforms. We...Apple Event Today: iPhone 18 Pro and iPhone Duo Cheat SheetTuesday September 8, 2026 10:24 am PDT by Tim HardwickApple's biggest event of the year is almost here, and all eyes are on Cupertino. With the first foldable iPhone expected to headline Apple's "Surprise and Shine" event on Wednesday, September 9, at 10:00 a.m. Pacific Time, the rumor mill has been running full throttle, fuelled by the biggest single design change in the life of the iPhone. To get you up to speed, here's a quick reference...Apple Says iPhone 18 Pro Max Sold in U.S. Differs in One WaySaturday September 12, 2026 3:27 pm PDT by Joe RossignolAs noted by Nicolas Lellouche, who writes for the French tech website Numerama, Apple has updated its tech specs pages for the iPhone 18 Pro and iPhone 18 Pro Max to clarify which models are equipped with its new C2 cellular modem and where. Apple now says the iPhone 18 Pro has a C2 modem worldwide, while the iPhone 18 Pro Max uses the chip in every country except for the U.S. According...