AT&T has acknowledged that some iPhone 18 Pro Max units on its network cannot reliably make calls, send texts, or use data. The carrier sent customers a text message on October 1 telling them to install iOS 27.0.1 immediately.
The full text of the message was shared by MacRumors, and it follows about a week of complaints from owners who lose service and watch their phones drop into SOS mode. Threads across the Apple Support Community, Reddit, and MacRumors Forums show at least thousands of affected users.
AT&T’s Own Text Warns That Some iPhone 18 Pro Max Phones Cannot Reach 911
The message tells customers that an important Apple software update is available for their iPhone 18 Pro Max. It then spells out the risk.
Some phones may be unable to complete calls/text/data, including to 911.
AT&T tells customers to open Settings, tap General, then Software Update, and install iOS 27.0.1. Anyone with questions is told to contact AT&T or Apple.
Apple released iOS 27.0.1 on September 28, three days before the text went out. Its release notes cover a Face ID fix for the iPhone 18 Pro models and do not mention a cellular fix.
Many Owners Say iOS 27.0.1 Did Not Fix the Signal Drops
Affected iPhone 18 Pro Max owners cannot connect to AT&T for calls, text messages, or data. For some the loss is constant, and for others it comes and goes. The phone typically switches to SOS mode when it happens.
A large share of those owners say installing iOS 27.0.1 changed nothing. Apple has not commented publicly, and the cause has not been confirmed. Separately, iPhone 18 Pro owners have reported that iOS 27.0.1 left the speaker crackling in place.
The US iPhone 18 Pro Max Is the Only New iPhone With a Qualcomm Modem
The iPhone 18 Pro Max sold in the US is the only new iPhone from the September event that uses a Qualcomm modem. The iPhone 18 Pro and the iPhone Duo use Apple’s C2 modem worldwide, and so does the iPhone 18 Pro Max in every other country.
It is unclear whether the modem is a factor in the AT&T problems. The US model also differs from the other regional versions in battery capacity and SIM support.
Buyers still choosing a carrier can compare iPhone 18 Pro carrier deals from AT&T, T-Mobile, and Verizon. Another update such as iOS 27.0.2 would be needed if the fault turns out to be in software.
