It is easy to use Skype to call a contact or company.
You need to have a field that is with the phone number format so that will be clickable. When you press the number it will open a window asking if you want to call from Skype or Skype for Business (you will need to check what is configured in the System Settings->General tab).
After that, it will show the Skype window to make the call and simultaneously it will open a phone call activity in the CRM so you can start writing any information about the call.
Hope this helps