Niklas Zennstrom and Janus Friis kept hold of ownership of the technology at the heart of the Skype service when they sold the company to eBay in 2005 for $3.1 billion. Skype licensed the technology from Zennstrom and Friis's company, Joltid.
Joltid was sued by eBay in a UK court in a licence dispute over the peer-to-peer technology in a case that is expected to reach court next year.
It has now filed a US suit against eBay and the investors who have agreed to buy a 65% stake in Skype for $1.9bn. That consortium is led by Silver Lake and including Index Ventures.
The suit also includes Mike Volpi who until a few days ago was chairman of another Zennstrom and Friis company, Joost. Volpi had joined Index Ventures and Joost said that it was investigating his conduct.
Joltid claims that it is due $75 million per day in damages for what it says is eBay's ongoing infringement of its rights, according to news agency Reuters.
"The Skype companies have continued to infringe Joltid's copyrighted works on a massive scale," the lawsuit said. "Each day that the Skype Companies continue to make available its Internet telephone software for download, Skype users download Joltid's copyrighted works approximately six times per second."
EBay told Reuters that the claims were baseless. "Their allegations and claims are without merit and are founded on fundamental legal and factual errors," it said.
The case asks a Californian court for an injunction against eBay's use of its technology. EBay is reportedly developing its own version of the peer to peer software.
