Free, unless you want to make calls to phone numbers from Skype.
The top VOIP providers at the moment is Vonage and Skype. Both Vonage and Skype offer business packages at a reasonable price.
Skype is the easiest way to make international calls. Skype offers memberships at a very low price and has other offers that can be useful to your company
You can Skype on the downloaded program of Skype
You do not need your Skype number to make Skype to Skype calls. You can log into your Skype account with your recently made ID and password.
Newer models of laptops are coming equipped with Skype, but that also means there's a higher price tagged on. Even though you can install Skype yourself on a cheaper computer, it would probably be wisest to spend the extra money for a smoother running computer.
If you have created your Skype ID recently, then you will not your number to make Skype to Skype calls. You can log in with your Skype ID and password to make calls.
Yes, you can make Skype to Skype calls with just your ID and password, you don't need your Skype number.
You can download Skype from Skype's Website!
For some Features of Skype you need Skype Credit!
All Skype to Skype calls are free, regardless of location.
I believe it's like mobile credit, with Skype, you can call people on Skype for free, but calling mobiles via Skype costs Skype credits.
Skype on a computer to Skype on another computer is 100% free, regardless of locations.