How to set up a VLAN for VoIP
Separating Data and Voice
No matter what kind of VoIP infrastructure you use - whether it's hosted PBX or an in house one, you need to manage your network in such a way that there's always sufficient bandwidth for VoIP to operate. This management has to take place on your network and is distinct from the maintenance of the VoIP network at the ITSP's end. This is because one Internet connection will be used for both browsing the Internet as well as talking over the VoIP network. While most of the time there isn't a problem, Internet usage can spike when people are watching a video or downloading a large file. During these times, it's important for VoIP to still have the necessary space to operate and that requires setting up rules which allow it to happen.
There are several approaches to this, two of which are QoS and VLAN. QoS stands for Quality of Service" and involves telling the routers what parameters it should apply to different types of traffic. You can always tell the routers to prioritize VoIP traffic and do away with VLANs entirely. In some cases, VLAN and QoS are used interchangeably because they accomplish the same thing but in different ways.
While you can use a QoS approach, a VLAN can guarantee that there's always a dedicated line for VoIP.
Setting up a VLAN
A VLAN can be quite easily set up using commands fed into the switches. Depending on the company which manufactures your network equipment, the commands can vary - sometimes between different models as well. Cisco switches are varied and VLANs can be created using a simple command like: vlan [number]. After creating it, you need to name it for easy reference and assign ports to it. Contact your VoIP provider for help in this if necessary. After all, it's in their best interests to make sure you have a great experience using VoIP and their network professionals will be able to give you some advice on how to fine tune your VLAN configuration.
One might wonder why not use a subnet for creating the separate network instead. The reason is that subnets typically depend on the physical location of the systems and such a system might not be at all suitable for the deployment of VoIP. Moreover, VLANs are nicely scalable as the size of the networks increase.
If you've opted for a hosted PBX plan, setting up a VLAN is probably the only management required at your end. You don't have to do any of the complicated stuff like SIP proxy servers configuration or or configuring HD voice IP services.