Canada's second-largest telephone company, Telus, has announced that it will block direct-dialed calls to Nauru.
The company says this is to stop so-called modem hijacking scams that run up big phone bills for unwitting customers.
Telus says from July the 1st calls will have to go through an operator if they are made to Nauru, Guinea-Bissau, Guyana and Sao Tome.
Modem hijacking usually affects subscribers with dial-up connections who unknowingly download programmes from some Web sites or pop-up windows.
Telus says this causes their modems to dial international phone numbers, resulting in long-distance charges.