I'm speaking from personal experience. Two years out of this place and my quality of life has skyrocketed. I enjoy my work again, I have enough free time to spend with my family, and my health has improved drastically - I was even able to get off a medication I thought I was stuck with for the rest of my life.
I still have so many friends at AT&T who are so unhappy. I know making a decision is hard, especially when the alternative is one big unknown. But just ask yourself, how much worse can it really be?