AT&T has completed fiber optics transmission links between Salt Lake City, Denver and San Francisco, as part of the telecommunication company's plan to create a nationwide fiber optics network.

"The completion of this fiber optics link will offer technological advantages such as high speed digital transmission of voice and data for businesses located in Utah," said Jack Schiefer, AT&T business markets group manager in the Mountain West region.Fiber optics are hair-thin glass strands that provide higher capacity and clearer transmission of digitized voice and data signals than copper-wired cables. A pair of fibers can carry more than 24,000 phone conversations at one time.

By 1990, AT&T plans to connect 350 U.S. cities with the glass fiber, digital transmission system, a spokesman said. AT&T recently completed a trans-Atlantic fiber-optic cable in a joint venture with British Telecom and France Telecom.

The transcontinental system is part of the "Worldwide Intelligent Network," servicing AT&T customers around the globe, he said. It also complements the company's other transmission systems, including coaxial cable, radio and satellite.