Hi guys to answer your questions : Ulra VPN works for my magic jack and skype out with no problems specialy when it connects to the US VPN server it much more stable. I never got any certificate errors, infact if you contact magic jack support online they recommend Ultra VPN.
Again guys there are TONS of free and paid VPN services, all you need to do is google it.
To asnwer adiab's question: Inorder to make you Linksys VOIP work you will have to share the VPN connection over your network. When you connect to Ultra VPN or any other service its only working on that computer being connected.
Vonage or any other VOIP machines will either need a VPN capable router, or a computer with 2 ethernet connections with the VPN internet sharing option selected...
Here is a simple way that I have done inorder to make my vonage work.
I had an old laptop with a wireless card (WIFI) and a network card. I connected to my home internet through WIFI. then signed up to
www.vpngates.com they gave me the sever address user name and password. I created the vpn connection then I made sure to select internet sharing on that connection.
Finaly I connected my vonage devise to the network card of that laptop, once my VPN is connected my Vonage works Just fine.