With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
ccmVMailDevDirNumIndex
Cisco Call Manager V Mail Device Directory Number Index
1.3.6.1.4.1.9.9.156.1.12.2.1.1
An arbitrary integer, selected by the local system, which identifies a Directory Number of a Voice Messaging Device.
Back to CISCO-CCM-MIB MIB page.
IPHost Network monitor allows you to monitor ccmVMailDevDirNumIndex 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.
