Since the issue is very specific to accessing voicemail and doesn't impact functionality of Webex in any other way, Departmental Support does not recommend downgrading for customers that don't use this feature.  Departmental Support is also temporarily suspending push updates for Webex until the issue is resolved.  Cisco is expected to provide an update to Webex in the fall to address this problem, at which point Departmental Support will remove this offer and resume Webex updates.