MCI Communications Corp. has divided up its marketing operations to match the regional geography of the seven divested Bell operating companies, a move the company says will enable it to compete against American Telephone & Telegraph Co. more effectively.

Edward W. Carter, who helped devise the marketing strategy, announced his resignation as senior vice president of marketing for MCI last week to start his own consulting business with MCI as a major client. MCI's decentralized marketing strategy is a good idea, he said, but he added that the company's national marketing also must stay strong to weather intense competition in the marketplace.

Customers are now being asked to choose a long-distance company for easy "Dial 1" service under the equal access process mandated after the Bell System breakup. Equal access eliminates the lengthy codes a customer had to dial previously to use a long-distance service other than AT&T.

Last September, MCI placed 55 of its 120 marketers into new regional offices set up to geographically mirror the seven regional Bell operating companies. The goal was to put the marketing operation closer to the regional Bell companies, which mechanically connect MCI to local networks.

The reorganization helped in some respects, but it also left the national marketing operations somewhat diffused, said Carter.

"The frustration is there are many things we need to do in the new system, and each division must agree to do it," he said. "It's hard for anyone trying to build new programs to then spend the extra time to get every single person to say 'fine.' It's especially hard when you have fewer people."

Bert Roberts, president of MCI Telecommunications, the long-distance arm of MCI Communications, said the divisional structure will help the company establish business relationships with the regional companies and allow MCI to focus more on acquiring new customers.

"We do have to understand nationally how our products are moving through regions. I don't disagree with that," Roberts said.

MCI still has a centralized marketing force that is "only going to present one image to the country" by keeping products, prices and advertising consistent, he said.

Industry experts say MCI's new marketing strategy is a positive step. "It's a response to the fact the market is opening up to become more competitive, and MCI feels it makes sense to deal with customers directly," said Marianne G. Bye, an analyst with Prudential Bache Securities Inc. "We think it makes a lot of sense."

Bye said many other long-distance AT&T competitors are going to have to follow MCI's lead as the market changes.

At the same time, other long-distance companies say a more fundamental question than how to set up marketing operations is whether the "equal access" process really promotes competition.