MCI Communications Corp. yesterday offered federal regulators a set of standards designed to prevent telemarketers from changing telephone customers' long-distance companies without their permission.

MCI's proposal, submitted to the Federal Communications Commission, was its salvo in a battle among long-distance companies over a telemarketing practice known as "slamming."

The plan came 10 months after American Telephone & Telegraph Co. sued Washington-based MCI, alleging that its telemarketing salespeople have switched AT&T's long-distance customers to MCI without their consent and misled AT&T customers in trying to win their business. MCI has called the charges "ludicrous."

The MCI proposal itself was prompted by telemarketing standards that AT&T proposed to the FCC early this year. The agency was seeking comment on AT&T's proposal to require each customer to sign a form before switching long-distance carriers. At present, the switch can be made on the word of a telemarketer that a customer has approved it.

"There is growing concern that the process of choosing a long-distance carrier be driven by informed choice of consumers, and not by deceptive sales or advertising practices of the long-distance companies," Eugene Eidenberg, MCI executive vice president, said in a prepared statement.

MCI's proposal calls for uniform, minimum disclosures in all sales pitches, monitoring of telephone sales representatives to make sure they follow the rules and outside verifications of whether consumers have really approved a change in their long-distance provider.

MCI also urged audits by independent, outside firms to make sure companies adhere to the standards, and backed giving customers free and convenient return to their original long-distance carrier if they didn't authorize a change.

"We're glad to see that MCI finally acknowledged its problem -- 'slamming' and fraudulent marketing practices ... ," said an AT&T statement on the MCI proposal.

John R. Hoffman, senior vice president of US Sprint Communications Co., agreed with the MCI proposal, but added, "We do almost all that ourselves."

Hoffman also said US Sprint opposes AT&T's proposal that customers be required to sign a form to switch carriers. "It does not solve the problem and it is anti-competitive because it protects AT&T's market share," he said.

Both Sprint and MCI favor letting customers switch services over the telephone, without signing a form first, and then having the change verified independently.

A congressional hearing on "slamming" is scheduled for next week.