ATLANTA, Georgia, June 3 -- BellSouth Corp. will test a new fiber-optic data line at 400 suburban Atlanta homes this fall as part of the company's plan to provide affordable high-speed Internet access. The fiber-optic line should transmit data faster than the digital subscriber lines (DSL) BellSouth has been marketing. The new technology also would allow BellSouth to compete with cable companies offering high-speed Internet access. The company expects the fiber technology to be as cheap as copper wire in two years as demand grows, according to BellSouth spokesman John Goldman. The fiber technology, called passive optical networking, doesn't require a power source between the company and a customer's home. BellSouth plans to charge the same rate for the fiber service as it does for its DSL service.