good thought but this is nothing more than havingt vonage still go to through the ATA which basicilly turns the vomnage into a bell-type POTS line then having to use up an FXO port on the asterisk box (either via a TDM400, an X100p or an SPA-3000).. so its kind of like voip-analog-voip. I dithced vonage because they wouldnt allow me to run my main number as a SIP device on a brign-your-own hardware type of plan.. ive got a couple of other VOIP providers (sixtel, broadvoice,junction) that im running or beta-testing.
I have however been succesful at connecting my asterisk to a mitel 3300 ICP at my office.. which means I dont have to deal with all the teleworker BS from mitel to have full access to my office phone system..
-Christopher