If you try to setup VoiceView Express for a CUE + UCM integration, and get the error:
Playback failed Authentication error. Report this error to your system administrator.
when you try to playback a message on Voiceview express, very likely you dont have the JTAPI user associated with the phone that use this service. Make sure the JTAPI user is associated to the phones that are configured to use VoiceView Express.