RCN then began its growth as a cable TV overbuilder, constructing competitor cable systems in markets that already had cable service. Most of its systems were partnerships with power companies, which provided rights-of-way on poles. RCN featured "triple play" television/internet/telephone service, though for some time its voice operations were largely resold incumbent telephone company lines. It purchased existing US East Coast ISPs Erol's Internet, UltraNet Communications, Interport, and JavaNet. On the West Coast, it purchased existing ISPs DNAI and Brainstorm. In Chicago, it bought into the market by acquiring overbuilder 21st Century Telecom. In Washington, D.C., they formed a 50/50 joint venture with local power company Pepco named "StarPower Communications" in 1999; they bought out Pepco's stake in 2004, and rebranded StarPower systems to the RCN name.