With IPHost Network Monitor you can run WMI Telephone Devices monitoring of various devices in your network.
To create a WMI monitor for Telephone Devices, provide host name (it must be a Windows host) and specify custom WQL query:
The number of telephone devices serviced by this computer.
The Telephony System
IPHost Network Monitor is an advanced and easy tool for monitoring LAN and WAN networks, network servers, workstations and TCP/IP devices. Use IPHost Network Monitor to monitor your servers, domains, computers and devices.