Which version of Microsoft Internet Explorer support WebRTC?
As of Sept 18 2015 Microsoft Edge (Spartan) is now supporting ORTC. Links and such are below.
BLOGS - http://blogs.windows.com/msedgedev/2015/09/18/ortc-api-is-now-available-in-microsoft-edge/
https://blogs.office.com/2015/09/18/enabling-seamless-communication-experiences-for-the-web-with-skype-skype-for-business-and-microsoft-edge/
http://blogs.skype.com/2015/09/18/skype-for-web-and-skype-for-outlook-com-update/
DEMOS on Edge Test Drive - http://dev.modern.ie/testdrive/demos/ortcdemo/ for Edge-to-Edge video calls
http://dev.modern.ie/testdrive/demos/twilioortc/ for Edge-to-Phone calls by Twilio
http://dev.modern.ie/testdrive/demos/simplewebrtc for Edge-to-Chrome/FF audio calls by &yet
Open Source projects for WebRTC-ORTC interop – from partners working closely with us
https://webrtchacks.com/first-steps-ortc/ - blog post and open source project by &yet
https://www.npmjs.com/package/ortc-adapter - open source project launched by Twilio
Hope this helps. Healy in Tampa
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.
UPDATED
Some people also report that IE supports WebRTC when using http://www.google.com/chromeframe
UPDATED
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
UPDATED
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/