Members of Congress are fed up with the state of cellphone coverage in the United States, and on Wednesday, they weren’t afraid to lodge their complaints personally — with the leaders of some of the country’s biggest wireless networks.

As Sprint and T-Mobile went to Capitol Hill to defend their $26 billion proposed merger, lawmakers buttonholed T-Mobiles chief executive, John Legere, and Sprints executive chairman, Marcelo Claure, on the frustrating inability to get a cell signal in many parts of the country, particularly in rural areas.