TULSA, Okla., Dec. 21 -- Williams Communications Inc. announced that its network unit has signed an agreement to sell services and fiber capacity to Worldwide Fiber Inc., in a deal valued at $26.5 million. Worldwide Fiber plans to use the fibers, which are located primarily in the northeastern US, to expand its national network. Under the 20-year agreement, Worldwide Fiber will provide Williams Communications with monthly revenue for collocation and network maintenance services.The two companies characterized their relationship as long-standing. Earlier this year, Williams Communications joined with a Worldwide Fiber subsidiary, Pacific Fiber Link, in constructing a multi-conduit fiber-optic backbone network between Sacramento, Calif. and Portland, Ore.