Apple today confirmed that a "small number" of iPhone 18 Pro Max users on the ATT network have experienced an issue that causes the device to lose cellular service, thereby preventing phone calls, text messages, and data from working. Thousands of users complained about the issue across the Apple Su pport Community and other platforms. Apple said it released iOS 27.0.1 earlier this week and an ATT carrier settings update earlier today to help prevent more iPhone 18 Pro Max users from being impacted by this issue going forward. In a statement shared with MacRumors, Apple strongly encouraged all iPhone 18 Pro Max users to update to iOS 27.0.1 now. To install the update, open the Settings app on your iPhone and tap on General → Software Update. The carrier settings update for the iPhone 18 Pro Max will automatically download for ATT users over the next 14 days, according to Apple. To manually trigger the update, users can open the Settings app and tap on General → About. Apple's full statement:We have identified an issue affecting a small number of iPhone 18 Pro Max users on the ATT network that may cause a device to lose service and be unable to make calls. 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. These updates together are meant to help prevent this issue from occurring.Notably, Apple said that iPhone 18 Pro Max devices that have been affected by this cellular issue on the ATT network cannot have service reactivated with a software update. Instead, Apple said the device must be replaced entirely, and it advises affected customers to contact Apple Support or ATT, or visit an Apple Store or ATT location. Apple said it has only observed this issue with iPhone 18 Pro Max users on the ATT network. No other iPhone models or carriers are known to be impacted. Apple did not disclose the underlying cause of the issue. 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 ATT issue. It is also unclear if there will eventually be an Apple Service Program dedicated to this issue. In the meantime, it sounds like Apple Stores will replace affected iPhone 18 Pro Max devices for free, so book an appointment with the Genius Bar if necessary.Related Roundup: iPhone 18 ProBuyer's Guide: iPhone 18 Pro (Buy Now)Related Forum: iPhoneThis article, "Apple Says iPhone 18 Pro Max Users With ATT Cellular Issue Need to Have Device Replaced" first appeared on MacRumors.comDiscuss this article in our forums ...read more read less