According to the district attorney's office, John Walter Raybon had a dispute with AT&T ... and went to the Lawrence Road location several times, threatening to sue.
Then prosecutors say Raybon called customer service in January of last year and threatened to bring a gun to the store.
Later that month prosecutors say Raybon showed up at AT&T with a loaded gun in his pocket.
He was arrested for unlawfully carrying a weapon and resisting arrest.
After that, officers say Raybon called AT&T to find out why his phone service was cut off.
He was transferred to the corporate security officer -- who is a retired Texas Ranger -- and allegedly told the officer he was going to destroy the lives of the ex-Ranger and the store manager.
Raybon was found guilty of retaliation, a third-degree felony and the 89th district court jury gave him the maximum punishment.
Copyright 2015 Nexstar Broadcasting, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.