voIP

Ive come across Freeworlddialup.com and skype.com

How easy would it be to setup a freeworlddialup.com type service ?

and can anyone give me more indepth info on how it works ?

thanks

http://iptop.net/eng/faq.html
That will give some quick answers to basic questions about the subject :)

Put simply the telephone calls on the internet are the soundwaves of your voice broken up into packets of data and sent out via a connection-less communication using the UDP protocol. The reason for this is because of the amount of traffic that would be required to validate all the data being transmitted, :) our brains fill in the small gaps in the sounds that we hear from the transmission (which are created from lost packets)