Finding a new role can be difficult, due to the sheer size of AT&T. Jobs that get posted on the internal job site, are frequently filled before they are posted, so don't bother, If you have excellent networking skills, you can get ahead of this process, "the well connected tipically are those who thrive in this toxic environment, often they that are the less competent at best.
The recent and upcoming mergers, are resulting in a very high number of lay-offs of well qualified people. Decisions on lay-offs are frequently determined by your Direct manager with little to no input from HR, ("very reliable source") Decisions are often made due playing favorites , along with the metrics that are difficult for an employee to change, welcome to our dysfunctional company