If you use Steam for voice calls, you’ll be pleased to know that Valve now incorporates the SILK codec as of today’s Steam client update. SILK is the same codec used and developed by Skype. This will mean much clearer communication between Steam calls.
SILK uses a dynamic bit rate protocol, which will increase bandwidth usage over the previous Steam-chat while delivering a better quality signal. Before Steam calls required 15 kbps of bandwidth, whereas SILK uses between 8 and 30 kbps. According to Valve this will also improve chat connectivity and reliability.
SILK is available now to all Steam users. No configuring is required, simply call a friend and hear the difference in call quality.
Portal 2 will be using SILK upon its release in mid-April for better communication during the co-op modes. In fact any game that can take advantage of Steamworks Voice API will benefit from SILK.