Have you used this site to reactivate your credit?
https://secure.skype.com/portal/settings/credit/reactivate
What amount is shown there to be reactivated?
This browser is no longer supported.
Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support.
I noticed that my unused skype credit can be used in Teams via its Skype Dial Pad feature so I wanted to reactivate my unused credits. I clicked reactivate and waited over 15 minutes multiple times on several days but my credit is still not activated.
Have you used this site to reactivate your credit?
https://secure.skype.com/portal/settings/credit/reactivate
What amount is shown there to be reactivated?
OK. This happens because you are in Japan. Due to special Japanese regulations, deactivated Skype credit cannot be reactivated.
Credit, once purchased, is supposed to be used. If not used within the last 180 days, it is lost.
https://www.reddit.com/r/mildlyinfuriating/comments/1i2l43z/skypes_absurd_policy_in_japan/
The special conditions for Japanese users are also mentioned in this support article:
"If you're in Japan, things work a little differently. Please refer to our Terms of Use for more information."
As far as I can see, the credit was purchased in Japanese Yen, and therefore the special Japanese regulations apply.
I'm not aware of any workaround with this situation, but you are always welcome to contact Online Support agent.
https://go.microsoft.com/fwlink/?linkid=2248238
The only what I can imagine might help is to change your billing address and currency, but I'm not sure.