Idea: Do not use ICE for NAT traversal (it will not always work). Do not use a public SIP server controlled by a third party (ever heard of spam?). Traverse NAT by getting a reachable IP address and running a supernode on it. Run your own _private_ SIP server (e.g. for just friends and family).

It's neat that this can all be made to run in the browser. But keep in mind that one company may end up with monopolistic control over the browser. It's certainly looking like this could happen. Again.

All this stuff runs just fine outside the browser. Supernode and SIP server can run as daemons.