With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
ciscoUnityEventUser
cisco Unity Event User
1.3.6.1.4.1.9.9.385.1.3.6
The user name of the user on whose behalf the event occurred. This name is the client ID if the event was actually caused by a server process, or the primary ID if impersonation is not taking place.
Back to CISCO-UNITY-MIB MIB page.
IPHost Network monitor allows you to monitor ciscoUnityEventUser on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco optical switches right now.