With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
ciscoUnityPortExtension
cisco Unity Port Extension
1.3.6.1.4.1.9.9.385.1.1.2.1.4
The extension for the port as assigned on the phone system.
Back to CISCO-UNITY-MIB MIB page.
IPHost Network monitor allows you to monitor ciscoUnityPortExtension on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco wireless switches right now.
