The codec, called , can deliver sound quality that captures the full sound of the human voice, according to Jonathan Christensen, Skype's general manager of audio and video. This "super-wideband" codec was introduced with the Skype 4.0 for Windows client, announced last month. Christensen unveiled the licensing program, which is live now, at the eComm conference in Burlingame, California.

The traditional phone system uses a narrow band for voice, from 400Hz to 3,400Hz, that cuts off high and low frequencies. This allows voice to be carried in a standard 64Kb per second (Kbps) channel but has disadvantages, such as blurring the difference between similar sounds such as "f" and "s."

VoIP can be carried on a fatter pipe than 64Kbps, so new codecs have been written to encode and decode voice at higher quality. With Silk, Skype can now reproduce the full range of typical voice frequencies audible to the human ear, from 50Hz to 12,000Hz, Christensen said. This will help callers identify different speakers on conference calls and make calls sound generally warmer, he said. At the same time, the new codec uses 50 percent less network bandwidth than Skype's previous version.

The company is making the codec freely available to third-party developers so they can use it in any device or application, with or without Skype, Christensen said.

"We think this is a way the whole industry can come up to a new standard of voice quality," Christensen said.