If you load balance between a Rogers and non-rogers connection, most likely your RHP service will not work. ISP's typically want to keep their VOIP service on their network, so they can ensure call quality end-to-end.
While you have good intentions by wanting to add redundancy to your network connection, this also adds MAJOR complexity to the way the phone service travels, and if it's not a Rogers connection, they have no control of the flow of voice traffic, thus [ultimately] creating a very large potential for poor call quality.
Essentially [in a nut shell] most ISP's will only allow their phone traffic on their network, because they can guarantee the quality of the call, the second it leaves their network, they cant.
Hope this helps--