Feb 22 (Reuters) - AT&T said late on Thursday that an outage that disrupted calls and text messages for thousands of U.S. users earlier in the day wasn't caused by a cyberattack.

"Based on our initial review, we believe that today's outage was caused by the application and execution of an incorrect process used as we were expanding our network," the wireless carrier said. (Reporting by Kanjyik Ghosh; Editing by Savio D'Souza)