actually, AT&T committed suicide in my opinion.
Bell Labs had been spun off with Lucent Technologies before SBC bought the corpse of the old AT&T.
It pains me to this day to see what has happened to one of the best (maybe the best) R&D organization this planet has ever produced.
I worked at the Labs twice, mid eighties to 1990, then left for Bellcore, came back mid 90s and worked there for a while. When they announced the AT&T, Lucent, and NCR split I believed that their days were done, and the NJ high tech economy was going to be very, very, very hard to live in soon. I was right. I'd already decamped for New England.
I'm amazed at how many bad management decisions killed them.