PHILADELPHIA, Sept. 12 -- Williams Communications Group Inc. has reached a settlement with bankrupt wireless company WinStar Communications Inc. that amended a 25-year pact to swap capacity on each others' networks. Williams said WinStar had delivered only 200 of the 270 antenna sites it had agreed to construct. Under the settlement, Williams will be allowed to use additional capacity on the existing hubs, and will cancel payments for hubs that were not delivered. Williams operates a nationwide fiber optic network to provide data to telecom carriers and other service providers. WinStar, meanwhile, transmits voice and data services using radio waves, rather than traditional copper or fiber optic communications networks.