AT&T is experiencing some issues right now that are leaving customers seeing “SOS” instead of their usual bars of service.

“We are working to address a software issue that may affect the ability of a limited number of our customers to connect to our wireless network. Keeping our customers connected is our highest priority, so we appreciate their patience as we work to resolve this issue,” said AT&T spokesperson Jim Kimberly in a statement sent to The Verge.

Kimberly also said that an explanation posted by The Mobile Report was inaccurate. That outlet said AT&T found internally that a failure at a switching center “has resulted in a cascade of problems, including service delays, the inability to provision new SIM cards, and, for many, a complete loss of network connectivity” that may primarily affect iPhones and other Apple devices.

Users on Reddit have also reported service issues on some Android devices.

On Tuesday afternoon, there was also a spike in user reports on Downdetector. There has been a dip in reports since the peak, but while writing this article, the Downdetector graph has started to creep up again.

Update, August 27th: Added statement from AT&T spokesperson.