WASHINGTON — People calling a federal phone number to order duck stamps are instead greeted by a phone-sex line because of a printing error the government says would be too expensive to correct.

The carrier card for the duck stamp transposes two numbers, so instead of listing 800-782-6724, it lists 800-872-6724. The first number spells out 1-800-STAMP24, while the second number spells out 1-800-TRAMP24.

People calling that second number are welcomed by “Intimate Connections” and enticed by a husky female voice to “talk only to the girls that turn you on,” for $1.99 a minute.

Duck stamps, which cost $15 a piece, are required to hunt migratory waterfowl. The government uses nearly all the revenue to purchase waterfowl habitat for the National Wildlife Refuge System. In 2006-07, the latest figures available, duck stamp purchases brought in nearly $22 million.

This year’s stamps, which feature a pair of northern pintail ducks, went on sale July 1 and are good through June 30 of next year. The error will not be corrected until next year’s duck stamps.

The Fish and Wildlife Service, which administers the program, printed about 3.5 million duck stamps attached to cards with the wrong number. An agency spokeswoman, Rachel Levin, said it would cost $300,000 to reprint them.

“I don’t know that it would be worth it to do a reprint,” she said Thursday. “That’s a lot of money we can be using for wildlife conservation. With all of the needs for conservation, it doesn’t make sense to divert money away from an important cause.” For those people who like to dial by letter, the card does include the proper 1-800-STAMP24.

“As best we know, it was a typographical error that was not caught,” Levin said, stressing that the stamps are still valid.

The agency first learned of the mistake a few days ago, when a duck stamp owner informed them of the glitch.

Levin said the agency has not received any complaints.

The error, which was first reported Wednesday by Denver TV station KUSA, is limited to self-adhesive versions of the stamps. The moistened version, which is printed in much smaller numbers, does not come with a carrier card.

The government uses a contractor, Ashton Potter Security Printers of Williamsville, N.Y., to print the duck stamps. Levin said she did not know whether the error was made by the government or by the company.

Ashton Potter’s president and chief executive, Barry Switzer, said that the company was provided with the wrong telephone number.

“We reproduced the wrong number correctly,” he said. “We regret this whole situation happened, but we did our job properly.”