The stadium opened as Safeco Field, with the locally based Safeco Insurance signing a 20-year contract to place its name on the stadium. With the contract ending after the 2018 season, Safeco chose not to renew it. The team then signed a new 25-year naming rights contract with wireless carrier T-Mobile US, the main American arm of German telecom giant Deutsche Telekom. The new name took effect on January 1, 2019.