My Samsung phone flagged this as a Potential Fraud. No message was left. Called back the number and says number disconnected. Blocked it

another call from the above number . I have no idea who its from. I have been receiving the same call from a varity of almost the same numbers . ie 9001 1556/ 1557 and so on . $#%^(&%#$

Keeps calling then hanging up, I have had about 30 calls from prefix 900115?? Each time I block caller they call again from the same number but they change last 2 digits.

Caller: Says government thing for swapping your hot water system

I have had 18 calls in the last 2 weeks from this 9001 number with all different last 4 numbers. Getting beyond the joke . Block every one just ring back on another extension.