Hi @IBN
You can look into blocking/whitelisting inbound calls with certain number patterns:
https://learn.microsoft.com/en-us/microsoftteams/block-inbound-calls
Block a number
https://learn.microsoft.com/en-us/microsoftteams/block-inbound-calls#add-a-number-exception
Add a number exception
https://learn.microsoft.com/en-us/microsoftteams/block-inbound-calls#add-a-number-exception
Here is also a nice article that talks about blocking spam calls:
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If this is helpful please accept answer.