OMAHA, Neb., July 25 -- Avaya Inc. is eliminating 457 jobs at its Connectivity Solutions plant. Most were given a month's pay, while some were offered early retirement. In April the company cut 220 jobs at the plant. The Basking Ridge, N.J.-based telephone systems maker is eliminating nearly 3000 jobs, or 11 percent of its work force, nationwide, as it accelerates restructuring because of slow sales. The Omaha plant, which employs 3200, makes copper and fiber optic cable and connecting apparatus, selling mostly to telephone companies and other communications-based businesses.