Apple has confirmed a hardware-level cellular failure affecting some iPhone 18 Pro Max units on AT&T’s network — and it cannot be fixed with software. Affected devices lose all cellular functionality: no calls, no texts, no data. IOS 27.0.1 and a carrier settings update released last week only prevent the issue. They do not restore service to already-broken phones. Users must visit an Apple Store or AT&T retail location for a full hardware replacement. Apple says the problem impacts a 'small number' of units, though thousands have reported it across support forums. No other iPhone model or carrier is involved. The flaw appears exclusive to U.S.-sold iPhone 18 Pro Max units, which use Qualcomm’s Snapdragon X80 modem. All other global variants. Including the iPhone 18 Pro and iPhone 18 Duo, ship with Apple’s in-house C2 modem and are unaffected. AT&T confirmed it’s working with Apple but declined to specify the root cause. Neither company has disclosed whether the issue stems from the modem itself, its integration, or a related RF component. Apple has not issued a recall or extended warranty coverage beyond standard repair terms. The fix remains reactive: replace the phone. No timeline for resolution has been shared. Meanwhile, the iPhone 18 Pro Max continues shipping globally. With no changes to pricing, specs, or availability outside this isolated hardware defect. The device launched at $1,399 in the U.S., ₹1,59,900 in India, and €1,499 in Germany. It goes on sale in Japan and Australia next week.