The basic concept of VLAN for VoIP is that you dedicate a seperate VLAN with a seperate subnet for Voice traffic. This keeps contention between data and voice to a minimum, and is easier to manage than a bunch of Quality of Service QOS rules on internal routers and switches.
A great resource from Cisco can be found at:
Here is an excerpt:
These are the voice VLAN configuration guidelines:
• You should configure voice VLAN on access ports.
• The Port Fast feature is automatically enabled when voice VLAN is configured. When you disable
voice VLAN, the Port Fast feature is not automatically disabled.
• If you enable port security on a voice VLAN port and if there is a PC connected to the IP phone, you
should set the maximum allowed secure addresses on the port to more than 1.
• You cannot configure static secure MAC addresses in the voice VLAN.
• Voice VLAN ports can also be these port types:
– Dynamic access port. See the “Configuring Dynamic Access Ports on VMPS Clients” section
on page 13-34 for more information.
– Secure port. See the “Enabling Port Security” section on page 17-5 for more information.
– 802.1X authenticated port. See the “Enabling 802.1X Authentication” section on page 8-8 for
– Protected port. See the “Configuring Protected Ports” section on page 17-3 for more
hope that helps