The worst are the ones that deliberately select a number in your own area code and local prefix; those are almost impossible to screen out because they look like a cellphone call from someone local.
That's the root of the problem that needs to be addressed and I think it's what most people mean by "spoofing" in this context. If your caller ID number isn't a number your company owns, we take you to a shallow grave and shoot you in the back of the head. Spoof numbers from within your company's phone number registry all you want. I don't care if the AT&T rep's desk phone caller ID shows up as AT&T's 800 number when they call me. I do care if a scammer in India's caller ID shows up as a number in my area code that has nothing to do with the call center he called me from. Eliminate that problem and you've pretty much solved everything.