Velox Networks provides an easy way to provide both QoS and Layer 2 VLAN Parameters both prior and post service deployment (if your switch only support L2 Tagging and not LLDP-MED)
Log into the Dashboard and click on "Users" >> "Edit" >> "Advanced Networking"
Once you have configured the settings – simply restart the devices (ensuring that the switch ports support both tagged and untagged data initially) and the phones will download and implement the configured L2 VLAN/DHCP VLAN tags and corresponding DSCP Values for Layer 3 Switches.