Voice VLAN is a technology that transmits voice data.
Data, voice, and video services are often transmitted simultaneously over a network. Voice services, in particular, require a higher forwarding priority than data or video services. When bandwidth is limited, voice data must have transmission preference over other types of data. This can be ensured by configuring a voice VLAN on the switch to transmit voice data and setting QoS parameters in the voice VLAN so that voice data is given preference when congestion occurs.