Update:

I just did the two simple simulring tests that I had wanted confirmation on. With simulring set for my cell phone, I dialed my voipo number (not from the cell phone, of course), and my cell phone rang. Answering the cell phone, the call was connected properly.

I then turned the cell phone off and repeated the test. As I expected, my cell phone's VM picked up immediately.

Final test--I dialed my voipo line from my cell phone, and it rang a few times before I disconnected the call. (If it had routed the call to my cell phone, my cell phone VM would have picked up immediately.)

I don't know what, if anything, was changed with the simul ring feature since I reported the issue, but it seems to be working properly now. As I said in my latest ticket update, I'd like to test a little more this afternoon before closing the ticket out, though.