I think you should do some more home work on this! But VoIP it is not just a dedicated server there is a lot more to it!!! routers, switches, session border controller's, tdm's and a lot more!!! I can recommend you a great Russian consulting company in NYC who can help you with all of this.
and also a government regulations, you need to get a few licenses that coast some real money.. no matter if you are in US or Russia or any other country each country requires you to have a licenses if you are providing a telecommunication services.