Real-time voice or video communication between users on mobile devices or computers
Unused Skype credit can be used to make phone calls from the Skype Dial Pad site on the Web:
https://calling.web.skype.com/
Just be sure to sign in to this site with exactly the same login as you have used with Skype. If you have used your Skype Name as the Login ID, the same Login ID must be used on this site.
In the case your credit was deactivated due to not being used within the last 180 days, this credit can be reactivated using this reactivation site.