I have two providers - PlusNet and Virgin Media - and the latter appears to use vicious traffic shaping on VoIP traffic. I thought it might be a good idea to block VoIP traffic on WAN2 (Virgin) to see if things improved. The problem, of course, is that I would no longer have the resilience circuit I would like. So another approach might be to favour VoIP on WAN1 (PlusNet) so that in the rare event of PlusNet failing, I still have some comms service.
How to I configure one or both of these ideas?

TIA.

Crispin