In exchange, prosecutors dropped three counts of wire fraud and one count of securities fraud. Hall, who also agreed to cooperate with investigators who are still looking into Qwest, faces up to a year in prison and a fine of up to $100,000.
Sentencing was scheduled for Jan. 14.
Prosecutors are not seeking restitution but U.S. District Judge Robert Blackburn could require it.
"These investigations are a marathon, not a sprint, and I think we're making good progress," Assistant U.S. Attorney William Leone said after the hearing. "Given the magnitude of shareholder losses, we need to be thorough, fair and deliberate."