Re-sell voice call traffic ( outbound )

I want to re-sell traffic of voice call for international countries. Please any advice / plan or calling platform to use?

you will want to start by finding a reliable voip or wholesale voice provider like twilio, plivo or voxbone. they will handle most of the routing and billing side. just make sure to check the rules and rates for each country, they can be really different. start small, test your routes and focus on keeping call quality solid before scaling up