Looking at http://trac.pjsip.org/repos/wiki/Getting-Started/Windows#BuildPreparationfor Windows It states for Video I would need to obtain the Windows SDK for Windows 7 and .NET Framework 4. Upon installation, I see it is a download installer. This is failing and suggests I get the ISO. I go to the ISO site at http://www.microsoft.com/en-us/download/details.aspx?displaylang=en&id=8442 The site has 3 different versions, which are x86, x64, and Itanium . I am wondering which version I should get, the x86 or x64? Looking at the download error, could it be possible it failed because I am on a 64 bit platform? Thank you.