TULSA, Okla., April 18 -- In what the company described as a step toward the creation of an all-optical network, Williams Communications has agreed to purchase Corvis Corp.'s suite of all-optical products. Under the terms of the two-year agreement between the companies, Williams will purchase up to $200-million worth of Corvis products upon the successful completion of a field trial to take place along Williams' Dallas-to-New York route. This month Williams will begin installing Corvis equipment that already has passed testing in Williams' Network Development Lab; the company expects trials to be completed by the end of July. The integration of Corvis' all-optical network solution into the Williams network is expected to allow us to scale to 2.4 terabits per second, representing a 30-fold increase over the current capabilities of fiber optic networks, said Frank Semple, president of Williams Communications.