(Telecompaper) The activist investor Elliott Management has launched a call for a strategic rethink at AT&T, saying it has a plan to turnaround the company's business and end the stock's underperformance. After buying USD 3.2 billion worth of AT&T's shares, one of its largest investments ever, Elliott said it sees as much as 65 percent upside in the share price by 2021 and wants to work with AT&T to implement the plan.