title: Error starting audio call using skype web sdk This person can't be reached right now. Please try again later
body: <p>I have a web app built using Skype Web SDK. When I try to start an audio call I get an error <strong>"This person can't be reached right now. Please try again later"</strong>. The person whom I am trying to call is available and I am also able to start an IM(chat) with him. Only when I start audio, it throws an error.
  I am using Skype For Business Online and not On Premise. The authentication is performed using Azure AD.
  I am getting an <strong>InvitationFailed</strong> error with a subcode of <strong>NotAcceptable</strong></p>