You need to enable VLAN's on the link. Presumably it's a wireless link? If so, go to the Setup page for your Bridge/AP and click the VLAN link. Configure your data (which you normally set as the default VLAN) and voice VLANs here using the same VLAN id's as on your wired LAN (make sure you enable 802.1Q Tagging). Once configured, again from the Setup screen click the Service Sets link and edit the default SSID to suit the data VLAN and then create a new SSID for the Voice VLAN. That should be pretty much it.
On the devices, configure them to use the appropriate SSID for the VLAN they need to connect to.
