Couple of things about Gizmo and Skype...

Unfortunatly the reason SIP is not more popular is because it's is ridden with problems. I've spent months trying out various clients including Gizmo and Wengo on three different routers. Port forwarding, STUN servers, RTP, UDP... are you kidding me! Don't get me started on trying to call someone on another SIP provider. I say SIP was dead before it started.

Skype in all it's evilnes, firewall or no firewall, just works. Period. You don't need to be sysadmin to set it up. Windows, Mac, Linux.

So, again, open protocols are great concept if protocol is good. In SIPs case, protocol is piece of crap, so way support it?

And another thing. If you talk to a lot of people in Europe, chances are they use Skype.

There, I said it.