AT&T has confirmed it is collaborating with Apple to address cellular service issues affecting a limited number of iPhone 18 Pro Max devices. Apple has released a software update, iOS 27.0.1, intended to resolve problems with calls, data, texts, and 911 functionality. Affected users have reported persistent or intermittent connectivity failures, often resulting in SOS mode. Thousands of customers have experienced these problems since the iPhone 18 Pro Max launched on September 18. The U.S. version of the iPhone 18 Pro Max, which uses a Qualcomm modem, is reportedly the primary model facing these issues. Other iPhone 18 models globally utilize Apple's C2 modem without similar reports. AT&T advises customers experiencing difficulties to update their phones and offers in-store support at Apple or AT&T locations. While iOS 27.0.1 was sent to some users, its effectiveness in resolving the cellular problems remains uncertain. Some customers have also faced challenges obtaining replacement devices under warranty. Today marks the final day for U.S. customers who purchased their iPhone 18 Pro Max on launch day to return it under Apple's standard 14-day policy. Apple typically resolves such concerns through software updates, with hope for a fix in future iOS releases.