[Serusers] ser configuration issues

I just started installing ser the other day and the installation was smooth and painless. I am know not quite sure about about the configuration files and how to set them. Here is my current setup -- I have a fedora 3 linux box obtaining a dhcp assigned address with currently no hostname set and no FQDN-- localhost.localdomain. I signed up the other day to iptel.org to register for a username and password -- ie, _example(a)iptel.org_ (mailto:example@iptel.org) . So i have 2 issues. 1. What should i specify in my /etc/profile for SIP_DOMAIN -- should i use my _example(a)iptel.org_ (mailto:example@iptel.org) or my internal lan address or my wan address available to the outside? 2. Same question when it comes to configuring the /usr/local/etc/ser/ser.cfg what should be listed on the listen parameters listen=127.0.0.1 listen=192.168.x.x or should it be the wan address also can i use the alias alias=_example(a)iptel.org_ (mailto:example@iptel.org) or should this be my machines hostname. Regards, Alfred