Online auctioneer eBay Inc. agreed Monday to pay at least $2.6 billion for Internet-telephony company Skype Technologies SA.

The total value of the deal may climb to $4.1 billion based on whether Skype meets a series of performance targets during the next three years, San Jose, Calif.-based eBay said.

Skype gives away software that lets people talk for free over the Internet using computers and microphones; a paid version, SkypeOut, allows calls to be connected to regular phones.