Right now I have 1 line on Vonage, and another on Voipo. I have 2 VTAs, 1 for each provider.

I'd like to switch my Vonage line over to Voipo (so I end up with 2 phone numbers on Voipo). What is the cheapest and easiest way to do this?

In the end I'd like to end up with 1 VTA, the Voipo one with one port being my existing Voipo number, and the other being my (old) Vonage number.