Despite the fact that Silk represents "a very significant chunk" of Skype research and development investments, the company is releasing it in order to make its popular peer-to-peer voice application work with a wide range of hardware and software clients, Christensen said. Those could include PC software, headsets, videoconferencing systems, cordless phones and mobile phones. Skype counts among its partners Asustek Computer, Plantronics, Arm, LifeSize and HelloSoft. Plantronics is set to announce on Wednesday a headset with its own sound card, which can use the Silk codec, according to Christensen.

Without a common codec, it would be hard for Skype to make its software work with this range of clients, Christensen said. Coming to agreement on which codec to use, given different licensing requirements, would be too complicated, he said. Silk is intended as an easy one for partners to adopt.

Skype is also moving toward making Silk interoperate with endpoints using SIP (Session Initiation Protocol), the emerging standard for signaling on IP telephony networks. The company is talking with Digium, the distributor of the Asterisk open-source telephony platform, and wants to make deals with other partners like this, Christensen said.

Silk can run on x86 chipsets for Windows, Macintosh and Linux systems, and the software has been run on Arm and MIPS chip platforms, according to Skype.

In addition to Skype 4.0 for Windows, the high-quality codec is available on Macintosh beta version 2.8, with a final Mac version coming in April. Linux is on a similar timeline, Christensen said.