With IPHost Network Monitor you can run simple snmp requests against a D-Link device in your network.
swVoiceVlanOuiMask
Switch Voice Vlan Oui Mask
1.3.6.1.4.1.171.12.74.3.1.1.2
The OUI mask indicates the valid bit of the OUI address.
Back to VOICE-VLAN-MIB MIB page.
IPHost Network monitor allows you to monitor swVoiceVlanOuiMask on D-Link device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring D-Link routers right now.