I had a client that was asking for this. Its hard to do, unless you use a third party app such as LiteScape or IP Celerate. You can have SNMP alerts sent from the switch to a collection point, that would then notify you about the OID sent from SNMP of that switch. You will get the MAC address of the disconnected device, but thats it. You would then need to do some sort of AXL/SOAP call into CUCM to query the MAC address to get the DN and possibly the user owner of the device. (or more information basically)
