For now IE doesn’t support WebRTC. Moreover, it seems like MS don’t plan to implement WebRTC. They announced a new technology called CU-RTC-Web – kinda Microsoft analog of WebRTC.
CU-RTC-WEB: http://html5labs.interoperabilitybridges.com/cu-rtc-web/cu-rtc-web.htm
Expected that this CU-RTC-WEB will be compatible with todays WebRTC.
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Some people also report that IE supports WebRTC when using http://www.google.com/chromeframe
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Microsoft announced supporting WebRTC in IE: http://blogs.msdn.com/b/ie/archive/2014/10/27/bringing-interoperable-real-time-communications-to-the-web.aspx
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While Microsoft will be adding WebRTC in IE, probably in 2015, to which version of IE is left to be seen: https://bloggeek.me/microsoft-browser-webrtc/