Internet telephone service Skype said on Wednesday that it would charge customers $29.95 a year for unlimited calling in the United States and Canada, a service it had offered free since May.

eBay Inc.'s Skype, which competes with traditional phone companies and Web operators like Vonage Holdings Corp. for customers, said subscribers who sign up for the plan before January 31 will get the service for half price.

The service covers calls to mobile phones or traditional wire line phones from computers or from a new category of Internet-connected phones that run Skype software.

Skype had been offering the computer-to-phone call service free since May as a promotion aimed at winning new customers.

Customers who do not want to pay a subscription could also opt to pay for calls at the rate of 2.1 cents a minute which it charged before the promotion.

Skype calls from computer to computer would still be free for its customers. The company said it would consider extending the service for international calls.

Skype said it had more than 136 million registered users globally at the end of September.