SpaceX's cellular Starlink system is thus far a “massive success, meeting or exceeding testing objectives," the company tells the FCC in a Thursday letter.The letter details SpaceX's progress on testing its “Direct to Cell” Starlink technology, which uses orbiting satellites to beam internet data to phones on the ground.The company previously took to Twitter to tout some of its successful tests, which recently included delivering downloads speeds at 17Mbps. The letter elaborates further, and says that SpaceX employees have been testing the technology’s capabilities in Redmond, Washington; Mountain View, California; and Kansas City, Kansas. “Among other results, the satellites have been able to communicate with multiple models of unmodified Samsung, Apple, and Google devices using (T-Mobile’s) PCS G Block spectrum, including in urban and rural areas, indoors and outdoors, and in clear sky and under tree cover,” the company says.