[Freeswitch-users] Best practices question about SIP registration

Please excuse me, I'm a VoIP newbie. I found the very helpful comment in conf/directory/default.xml. It says that the default domain is the IP address of the Freeswitch server. It seems to me that this could cause problems if the IP changed for some reason, or if the server has multiple NICs (which one does it choose in that case?) Is it better do just define a well known text string for the default domain, or even use a real DNS domain name? 2nd question is about SIP usernames. At least one phone I have found uses the MAC address as the default SIP user. Would it be better to avoid having a separate TFTP file for each phone, and just use the already unique MAC address as the user? -- Steve