how start-up a voip service

Hi,

in few words what I need as hardware for "host" a real number and then create virtual numbers and offer voip services?

If I understand well, I should have a normal PSTN line, buy a real number and point-link it to this PSTN line in my office. Then this line should be connect to a sort of "server" that is able to manage a lot of PSTN lines (1000? or unlimited?),

what else?

Can you tell me in few words the steps of how it should work and the hardware and software requirements?

How much can cost a cheap solution?

I would do this in Switzerland, so assume that I'm not in Usa and in Europe is a bit harder...

I'm agree to use an hosting too in Usa if is possible to be competitive too.

thanks

EP