With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
ccmeEphoneActiveDN
Cisco Call Manager Express Ephone Active DN
1.3.6.1.4.1.9.9.439.1.2.6.1.3
Current active DN (line) on the IP phone.
Back to CISCO-CCME-MIB MIB page.
IPHost Network monitor allows you to monitor ccmeEphoneActiveDN on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco switches right now.