My two cents - if the software in use can display the incoming phone number (and/or name) the software could be modified to do a validity check on the number to determine a) is it real, b) is it not in formatting compliance, c) trace back , d) and more depending on the analysis performed to identify bad phone calls. This would take time and money which most providers either do not want to spend, do not have resources (person power, money, equipment etc.) As to the limitation of the numbers you can block this too is (or should have been) a parameter setting that is changeable. Again this would involve time and money to modify. The question is where does a business want to spend their profits? Make life better for their consumer or their shareholders.
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