EBay Inc. is building new software to run its Skype Internet-calling service, a bid to sidestep a licensing dispute with Skype’s founders, who have threatened to take back the underlying technology.

The new software will be expensive and might not work, eBay said in a regulatory filing. The company said it might have to shut down Skype if the dispute with the founders isn’t resolved.

EBay Chief John Donahoe plans to hold an initial public offering for Skype in the first half of 2010.

EBay acquired Skype in 2005, though the rights to some of its so-called peer-to-peer technology remained in the hands of the founders.

EBay is suing a company owned by Skype’s founders, to prevent them from pulling the technology that runs the service.