Apple has confirmed a hardware issue affecting the iPhone 18 Pro Max on the AT&T network in the US. Devices show an "SOS" symbol, and calls, texts, and data stop working.
Apple says only a "small number" of users are impacted. It released iOS 27.0.1 and a carrier settings update to prevent the problem. However, these fixes won't help owners who have already lost their signal.
The iPhone 18 Pro Max is the only US model using a Qualcomm modem, though a direct link to the bug is unclear. Affected users should contact Apple Support or AT&T for a hardware replacement.
To check for updates, go to Settings > General > Software Update, then tap About under General to trigger a carrier settings update.
Source: Engadget · Summarized by HeadlinesBriefing