We are using a BR1 Mini as a dedicated VoIP gateway for a site
As you can see, all three WANs have the same priority.
These are the Outbound policy options available in the router.
Although this router is running a beta release of FW8.1.0, there has been no change in the routers options or configuration since this FW8.0.2 (FW changed about three days ago).
For configuring, we are using Google Chrome, we gave up on the other brands of browsers, finding Google Chrome worked best across all platforms (Windows, Apple & Linux).
Happy to Help,