(Telecompaper) The US Federal Communications Commission has approved the proposed merger of mobile operators T-Mobile USA and MetroPCS. The deal is expected to create a stronger fourth player on the US mobile market, boosting competition. While no conditions were attached to clearance of the deal, the commissioners Jessica Rosenworcel and Mignon Clyburn said they would hold the companies to their pledge to maintain job levels in the US. "The companies have pledged to me that they have no plans to close any domestic call centers, to move them offshore, to close any retail stores, or to reduce retail positions as a result of this deal," Rosenworcel said in a statement. The Communications Workers of America had called for the FCC to incorporate enforceable job protections for T-Mobile and Metro PCS workers in its merger review. The CWA said it was also disappointed the FCC did not bring the merger issue to a full commission vote, leaving the decision to the Wireless Telecommunications Bureau. "This action is unprecedented in a merger of this magnitude," the union said. After earlier clearance by the Department of Justice, the main hurdle remaining for the deal is shareholder approval. The vote among MetroPCS shareholders is scheduled for 12 April, and the company's board has recommended shareholders approve the transaction.