Calling All VOIP Experts

I have been thinking of some ways to transport regular analouge line over IP. So you plug your IP-phone on to internet, point it towards the dedicated IP..and get a ring tone. This way a line could be setup and calls made to that country as local charges as well recived from local callers at destination without incurring them long-distance charges. Something people do with vonage phones over here. So they get a US/Cad/UK number in saudi arabia as well place calls and recive calls without incurring callers long distance charge. However vonage doesnt cover asian countries..and my company calls a lot to China & Pakistan.