Apple confirms cellular problem on iPhone 18 Pro Max on AT&T; affected devices get replaced
A small number of iPhone 18 Pro Max units on AT&T lose their cellular connection and show “SOS” instead of the carrier name, so calls, texts and data stop working. Apple released iOS 27.0.1 and a carrier settings update to reduce the risk for other users, but devices that have already dropped out do not recover from it and need a hardware replacement. The US Pro Max uses a Qualcomm modem; the iPhone 18 Pro with Apple’s C2 modem is not affected.