T-Mobile USA's proposed merger with MetroPCS took a leap forward Tuesday with its approval from the Federal Communications Commission and the Department of Justice. Both agencies said the deal could increase competition in the mobile phone industry. MetroPCS shareholders still need to sign off on the merger in an April 12 vote, with two institutional investors in opposition arguing for better deal terms. In a letter to shareholders, MetroPCS aggressively defended the deal saying the carrier's debt would be no higher than that of rival carriers or its own historical levels. The carrier also said the merger carried a substantial premium for investors partly by saving money through consolidating its operations with T-Mobile.