Vyvx Inc., Tulsa, OK, and IXC Communications Inc., Austin, TX, plan to swap rights to use fiber on future fiber-optic routes, adding new markets for each company. IXC plans to swap rights to use inactive fibers in its 7000-mile system currently under construction from Los Angeles to New York for rights to use dark fibers on a 1600-mile route, which Vyvx plans to build from Houston to Washington, DC.