Just a quick suggestion. If you want a WORK AROUND for the "REN" issue; all you have to do is buy a "CORDLESS JACK". Even though cordless phones are so popular, they do still make cordless phone jacks.

Then, you plug one of the cordless adapters into AC power and the voip adapter output, and the other cordless piece you plug into AC power where you want the external bell. The external bell will get it's actual voltage to RING from the cordless unit and the AC power..... NOT from the voip adapter. Thus, the voip adapter won't have any problems with "REN" issues.

Yes, I've done this and it works. There are quite a number of types of cordless jacks and a number of voip adapters. So I can't tell you which cordless jack to try. Some use RF Radio (What I suggest). Some use filters and actually sends the phone signal over the AC Power lines. (Never had much luck with this type with my fax. (When I use to fax). I've used these cordless jacks on Fax machines, credit card machines, Directv Receivers, and external bells. Now; I no longer use fax, and the credit card and directv uses ethernet/wireless network instead of dial tone. I still use an external bell, but I have it wired in. I can't really explain it in a thread, because I have 10 phones wired in my house to voipo and it's a bit complicated so I don't hurt the voip adapter. Basically, instead of using the PAP2 voip adapter to RING the bell, I use an external power source for the external bell, and the PAP2 voip adapter simply triggers a very low current relay which in turn triggers the external voltage to the external bell.

But the cordless jacks do work. I had luck with the RCA and Philips models.