Underdog long-distance companies sometimes cheaper and better
Lesser-known long-distance carriers often cost callers less and sometimes provide better service than GTE Sprint, MCI, and AT&T, according to the Washington Consumers' Checkbook, a nonprofit consumer group here.
For many long-distance callers, Satellite Business Systems' Skyline service is 30 percent less expensive than AT&T's direct-distance dialing. Skline often beats Sprint by as much as 17 percent and MCI by 14 percent.
This information, along with detailed carrier-by-carrier cost comparisons, is contained in ''The complete guide to lower phone costs,'' a new book released by Consumers' Checkbook for $6.95.