Cisco is reporting the issue resolved.
[RESOLVED] Webex Meetings: Reports of users who are unable to connect to audio
Cisco Engineering identified an issue affecting services in the Texas data center. Some users experienced degraded in-meeting performance, audio disconnections or no audio options.
Update: Resolved at 1:56pm:
[RESOLVED] Intermittent issues within Mediasite
SonicFoundry has reported the intermittent issues with Mediassite has been resolved.