Internet telephony provider Skype announced Friday it now has more than 100 million registered users worldwide.

Skype, which was bought last year for $2.6 billion by online auctioneer eBay Inc. (EBAY), said it has nearly doubled in size from September 2005 when 54 million people were using the service.

Founded by the creators of Kazaa, the free music-sharing program that riled the music business, Skype gives away software that lets people talk for free from computer to computer, or pay a small fee to place and receive calls from regular phones.

Internet phone providers like Skype are creating upheaval in the telecommunications industry and putting pressure on traditional operators.

Their Voice over Internet Protocol technology is cheaper and more efficient than traditional circuit-switched phone systems, and VoIP usage figures to become more prevalent as broadband penetration deepens.