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.
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