PORTLAND – Regulators warned telephone customers Thursday that unscrupulous telemarketers are using the pending sale of Verizon’s land lines and Internet accounts in northern New England to FairPoint Communications to “slam” customers.

In Maine, a half-dozen complaints have been received from customers whose long-distance carriers were switched without their knowledge, and those likely represent the “tip of the iceberg,” said Fred Bever, spokesman for the Maine Public Utilities Commission in Augusta.

Regulators in Maine, New Hampshire and Vermont, along with federal regulators, have approved the $2.35 billion sale. The deal is expected to close at the end of March.

Utility regulators note that there’s no need for consumers across the region to worry about making changes to their long-distance accounts once the Verizon-FairPoint deal closes because there will be no change in rates or terms and conditions.

“Consumers should know that the switchover to FairPoint will not affect their existing calling plans, and there is absolutely no need for them to make any new arrangements,” Kurt Adams, chairman of the PUC, said Thursday.

“Slamming” happens when telemarketers get customers to switch long-distance phone service carriers without the customers’ knowledge.

In some cases, slammers falsely pose as representatives from Verizon or FairPoint. The slammers may claim to be calling to ensure that the transition to FairPoint is “seamless” or to offer a favorable calling plan that isn’t in fact favorable at all.

Thinking they’re receiving a legitimate offer, customers agree to the change. But when their phone bills arrive they discover that their service has been changed to a carrier they don’t recognize and don’t want.

Regulators say consumers can avoid being slammed by placing a “freeze” on their long-distance carrier by notifying their local telephone company. Also, consumers should read their bills carefully to make sure they haven’t been slamming victims, regulators say.

Slamming victims should not pay any unwanted charges and should notify their local carriers, along with their states’ regulators.