Additional features, settings, or issues not covered by specific Microsoft Teams categories
Remaining Skype credit cannot be transferred to Teams, but this credit can be used to make phone calls from Skype Dial Pad on the Web.
https://calling.web.skype.com/
Just make sure to sign in to this site with exactly the same account as you have used with Skype.
If your credit has not been used for more than 180 days, then this credit is now deactivated. Deactivated credit can be reactivated using this reactivation site.
https://calling.web.skype.com/account/credit_reactivation
With an active Skype Credit, a link to Skype Dial Pad site will also be available in Teams app.
https://support.microsoft.com/en-us/skype/how-do-i-make-a-call-in-the-skype-dial-pad