Vent cleaning scam.

Robocall promoting vent cleaning.  The number is spoofed, as I checked on TelcoData and the 408 exchange in the 408 area code is not assigned to a known phone company.

You would think that the phone company(ies) could examine the caller ID data and automatically block calls that come from inactive exchanges.

ref: https://www.area-codes.com/exchange/exchange.asp?npa=408&nxx=408

I do not have heating ducts, and when I tried to call them back, to harass them, the number "is no longer in service..."