Plessey Co’s strategy of ignoring the highly competitive US market for main exchanges and instead pursuing more numerous but less fiercely-fought bids for smaller secondary exchanges is beginning to pay off handsomely with a $100m order for smaller digital exchnages to its Stromberg-Carlson unit from BellSouth of Atlanta. The order is for 60,000 lines for the South Central Bell unit in Alabama between 1988 and 1990, with about 15,000 lines to be delivered next year. The switches will be manufactured by Stromberg-Carlson in Florida. Plessey now looks for orders from other BellSouth operating companies and from others of the regionals.