The problem with spoofing is that there are legitimate uses of it. It's probably solvable by only allowing spoofing of numbers you actually own (so if a hospital has 20 phone lines, they can spoof their publicly posted phone number, but random spammers can't spoof your neighbour's phone number).
The fact that the phone companies haven't done this or much else yet goes to show how little they care.
The fact that the phone companies haven't done this or much else yet goes to show how little they care.