raytaylor: I always thought that the ONT did the vlan tagging (like a managed switch does). So each ISP operating on the fibre network had their own vlan on the chorus network and their assigned port on the end user's ONT was also tagged with that same vlan ID. So multiple services could be provisioned to the same ONT by assigning each port with a different VLAN.

I assumed that when combined with DHCP option X? it would mean that any router could be used and just plugged in and end up working because the ONT inserted the line ID which the ISP's DHCP server would use to look up the customers IP address to assign.

Am i missing something here? Am i reading it right that you need to set your WAN port on your
router to also have a VLAN tag?