1-1 
1  Voice VLAN Configuration 
When configuring voice VLAN, go to these sections for information you are interested in: 
z  Voice VLAN Overview 
z  Voice VLAN Configuration 
z  Displaying and Maintaining Voice VLAN 
z  Voice VLAN Configuration Example 
Voice VLAN Overview 
Voice VLANs are VLANs configured specially for voice traffic. By adding the ports connected with voice 
devices to voice VLANs, you can have voice traffic transmitted within voice VLANs and perform 
QoS-related configuration and prioritization for voice traffic as required, thus ensuring the transmission 
priority of voice traffic and voice quality. 
How an IP Phone Works 
IP phones can convert analog voice signals into digital signals to enable them to be transmitted in 
IP-based networks. Used in conjunction with other voice devices, IP phones can offer large-capacity 
and low-cost voice communication solutions. As network devices, IP phones need IP addresses to 
operate properly in a network. An IP phone can acquire an IP address automatically or through manual 
configuration. The following part describes how an IP phone acquires an IP address automatically. 
 
 
The following part only describes the common way for an IP phone to acquire an IP address. The 
detailed process may vary by manufacture. Refer to the corresponding user manual for the detailed 
information. 
 
When an IP phone applies for an IP address from a DHCP server, the IP phone can also apply for the 
following extensive information from the DHCP server through the Option184 field: 
z  IP address of the network call processor (NCP) 
z  IP address of the secondary NCP server 
z  Voice VLAN configuration 
z  Failover call routing 
Following describes the way a typical IP phone acquires an IP address.