Thousands of AT&T subscribers in the US were faced with an hours-long network outage on Tuesday, leaving them unable to make or receive calls, send text messages or access the internet on their iPhones.

iPhone users began flooding AT&T’s Help channel on X (formerly Twitter) and the Downdetector site around 2 p.m. PT with complaints about being stuck in Emergency SOS via Satellite mode. Whenever iPhone users have no cellular service or Wi-Fi, they will see an SOS in the corner of their iPhone, indicating that they can use Emergency SOS via Satellite to get emergency assistance.

Read more: If your iPhone is stuck in SOS mode, here’s what to do

AT&T indicated that there was a software issue and that a fix was being worked on.

“We are working to resolve a software issue that may impact the ability of a limited number of our customers to connect to our wireless network,” AT&T said in a statement. “Keeping our customers connected is our top priority, so we appreciate their patience as we work to resolve this issue.”

An updated status statement from AT&T at 7:55 p.m. PT indicated the issue had been resolved.

SOS mode is a feature Apple unveiled in 2022 that allows users to contact emergency services and share their location with them, even if they don’t have cellular service. Emergency SOS via Satellite, which is available on the iPhone 14 and later phones, has been critical in helping people stranded without phone signal reach emergency services. Last year, for example, it helped a couple trapped in their car during the Maui wildfires.

Apple did not immediately respond to a request for comment.