With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
ccmRejectedMediaDevices
Cisco Call Manager Rejected Media Devices
1.3.6.1.4.1.9.9.156.1.5.13
The number of media devices whose registration requests were rejected by the local call manager.
Back to CISCO-CCM-MIB MIB page.
IPHost Network monitor allows you to monitor ccmRejectedMediaDevices 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.