If this is a ZD managed network, you can tag vlan to specific wlan in the Advanced Option field. Vlan 1 = untagged traffic, if you make the voice wlan and put in an access VLAN of 2, all client traffic associated to that voice vlan will be sent out tagged with VLAN 2.
When you create a wlan marked as GUEST wlan, it is not necessary applying any VLAN tag, it only put client into the "Guest Access" (Configur>Guess Access) page which will allow you to enable onbording, or have the user enter a username and password or just have them read a Terms of Use page, BUT the client is sill on the untagged vlan unless you set it in the Advanced Option field.
IF you do add a VLAN (other than Access VLAN 1) you need to make sure that the VLAN has a route out to the internet.