Sorry to hear that, I was hoping you'd have gotten the offer and I'd kinda know someone going into the training. I've read a lot of the forums here and if I could take anything out of it is to keep applying. Maybe they had a previous AT&T employee or a transfer.
When I worked at Best Buy I had the job title of Operations Coordinator, it was like a mini supervisor role. Our Store Manager ended up getting promoted, the Ops Manager got the Store Manager, the Ops Sup took over as the new Manager, so I was a shoe in for the Sup role. I interviewed for it, nailed the interview, but at the same time the position opened up a previous Best Buy employee had moved to the area with her husband (who was military) and they ended up hiring her as the new Sup because of her years more experience at Best Buy. I was atleast able to move up to Full Time even though I didn't get the Sup spot.
Keep your head up, keep applying and definitely keep us posted when you get the job!