The Fish and Wildlife Service said the misprinted numbers -- which connect callers to a recorded female voice that promises them they can "talk only to the girls who turn you on" for $1.99 per minute -- appear on about 3.5 million of the federally-issued cards and the service does not have the funds to reprint them, the Minneapolis Star-Tribune reported Thursday.

Rachel Levin, a Fish and Wildlife spokeswoman, said the misprint on the Migratory Bird Conservation and Hunting Stamp -- commonly referred to as a "duck stamp" -- is "an unfortunate typographical error" that her agency "really regrets." However, due to the costs involved in reprinting, she said the misprinted stamps will continue to be sold.

The correct number, 1-800-782-6724, is meant for hunters wishing to purchase additional duck stamps. The misprinted number instead connects to a phone sex line called "Intimate Connections."

"The stamp is perfectly usable," Levin said. "It will just be a lot more interesting for people now."