VLAN configurations vary depending on the phone Brand however they all function the same way, the packets need to be tagged and then you can route the packets tagged to the connection you want to use for voice. But the phones would need to be able to connect to the internet before adding the parameters.
The reason for this is the following: in the case of all our phones, configurations are retrieved by the phone as soon as the phone is connected to the internet. So any VLAN parameters will be set on our provisioning platform. And the process works as follows:

1.- The phone connected to a regular internet connection with no VLAN will search for the Manufacturer's Provisioning server.
2.- The phone is redirected to our platform and it will download all configuration files with Sip Credentials, VLAN configuration, etc.
3,- After the phone has done this it will tag voice packets with the correct tag (VLAN 12 for example) and you will be able to route them as you please. Be aware that after the phone downloads the configuration is when you should route the tagged traffic.
4,- If the Phone has a computer connected to it the computer data packets will not be tagged so you just need to route those as well.

We don´t setup or require manual configurations on your phones, and this is the way we can configure your phones for you to use a VLAN dedicated for voice, just request the VLAN ID you need added and we will do this please specify the devices that need the configuration.