With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
ccmVMailDevInetAddress
Cisco Call Manager V Mail Device Inet Address
1.3.6.1.4.1.9.9.156.1.12.1.1.7
This object identifies the IP Address of the Voice Messaging Device. If the IP Address is not available then this object contains an empty string. The type of address for this is identified by ccmVMailDevInetAddressType.
Back to CISCO-CCM-MIB MIB page.
IPHost Network monitor allows you to monitor ccmVMailDevInetAddress on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco mobile switches right now.