Route10 - adding tagged subinterfaces to WAN

Is it possible to add a tagged sub interface to the WAN interface on the route10?

Use case:

My internet service is delivered untagged but I have an office phone that i’d like to use that is being delivered tagged on vlan 19.

I tried clicking the + next to the wan interface thinking it might let me add it from there, and it did add another wan interface, just not as a sub of the existing.

If it’s not possible, is that something that could be looked into to add in the future?

This might just be an ISP specific feature but it would also be useful for ISP’s delivering transparent lan services between sites. Tagging/pushing the vlan for transport across the ISP network but popping/untagged for delivery on a port on the route10 or connected switch.

Another ISP use case would be multicast tv - which combined with that functionality for internet, phone and tv would make it a pretty affordable easily managed triple play device.

Thanks!