By Beth Kobliner

(MONEY Magazine) – Why does a five-minute call from Washington, D.C. to Cleveland cost $1.40 from one pay phone and $5.65 from another? It's the latest entry in the annoying annals of telephone deregulation. A recent court ruling requires Bell regional companies to give owners of the nation's 1.7 million public pay phones leeway in selecting telephone companies for operator-assisted and long-distance service. Though most have chosen AT&T, MCI or Sprint, some opted for one of the 90 smaller alternative-operator service (AOS) companies. There's the hang- up. The AOS branch of the industry has a reputation for reaching out and gouging -- charging 50% to 200% more than AT&T, according to the Telecommunications Research Action Center, a Washington, D.C. group begun by Ralph Nader. But you can circumvent an AOS company by instead hooking up with your own long-distance carrier. MCI and Sprint -- which often charge 10% less than AT&T -- provide instructions right on their calling cards. AT&T customers should follow these steps to minimize their pay-telephone charges: -- For direct calls, dial 10ATT, then 0, and then the area code and phone number. After you hear a tone, punch in the 14-digit authorization number on your calling card (it's usually your phone number plus your assigned four digits). -- To reach an AT&T operator, just dial 10ATT, then 0. If you used an AOS and think you were overcharged, an S.O.S. might provide redress. For beefs over interstate calls, send details and a copy of your phone bill to the Enforcement Division, Common Carrier Bureau, Federal Communications Commission, Washington, D.C. 20554. For intrastate AOS gripes, write to the public utility commission, generally in the capital of the state where the pay phone was located.