Apple has identified an issue impacting a small number of iPhone 18 Pro Max users on AT&T. These affected devices may lose service and be unable to make calls, displaying "SOS" in the status bar. The problem is specific to the iPhone 18 Pro Max models in the U.S., which use Qualcomm cellular modems. It does not affect other iPhone 18 Pro models or users on Verizon and T-Mobile. Apple has released iOS 17.0.1 and is issuing a carrier settings update today to help prevent the issue. These updates are intended for devices that have not yet lost service. Unfortunately, the software updates will not restore service for iPhones that have already experienced the problem. Users whose devices have already lost service will require a hardware replacement. They should contact Apple Support, AT&T, or visit an Apple Store or AT&T location for assistance. This issue seems linked to the Qualcomm modem in conjunction with AT&T's network.