Hi all,

I'm interested in using VOIP, and I've read the howto, but I still have a lot of questions:

Is it possible to run your own server? Could such a server be used to make calls to landlines? Or in other words, what are clients like Skype and Ekiga interacting with, how does it work, and can it be done at zero cost?

If using a client like Ekiga or Skype, what sort of (iptables) firewall adjustments are necessary?

Are there any publicly accessible machines that can be contacted via VoIP, for testing purposes? I'd like to be sure my system is working properly before advising less technically inclined people on setting up their systems.
EDIT: It looks like Ekiga has such a system. You can dial sip:500@ekiga.net for an echo test.

What about encryption? Can either skype/ekiga/gnomemeeting/others encrypt my voip traffic?

And what about receiving Windows systems? What software do they need, is it free, and can they handle encryption (if it is available)?

I know that's a lot of questions; feel free to answer only those that interest you. Thanks!

Usually you need a VoIP service provider for general Voice over IP connections to the world. However, it is possible to configure asterisk to act as a VoIP server on a basic debian box for just anyone who is prepared to sign up with you (usually acts as a switchboard for a large business).

For just setting up at home: http://asteriskathome.sourceforge.net/