best options for international communication

I am in the process of starting a company which will require me to call business owners from around the world. I am trying to find the cheapest and most effective way to do this. I will also be in multiple countries throughout this process. Is it smarter for me to spend a lot on a very high phone bill or use some sort of VoIP service like Skype?

Thanks for the help.

via Cell Phone Forums (French) http://cellphoneforums.net/fr/general-cell-phone-forum/t362644-best-options-for-international-communication.html