This guides clearly shows how SFB clients negotiated, determined and settled most preferred IP candidiate for optimal communication betwen them.
This guide helps;
To find out exactly which public and private IPs SFB client used for communication
To troubleshoot SFB client registration issues
To troubleshoot Firewall issues
To troubleshoot Audio Video media path issue
The guide is downloadable at https://goo.gl/G7FjZ8