Need suggestion regarding setting up commercial voip line

I am looking for ideas/paths /ways to setup a voip line on commercial basis. I have read quite a few postings here, and thought to ask for help. It’s a project starting from the scratch and my lack of knowledge in this telecomunication field makes it more harder!

This is what I have in mind :

I want to setup a company providing tele calls from here to one of the south east asian countries. I am not looking to open another calling card company , rather a monthly subscriber fee based voip line.

I appreciate any idea,help, guide suggestions whatever you can porvide very much.