Skype application was retired in May this year.
Teams Free application does not have the option to make phone calls. However, if you still have some remaining Skype credit, this 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 login to this site with exactly the same account as you have used with Skype.
In the case your credit has expired due to not being used within the last 180 days, this credit can be reactivated from this credit reactivation site: