Well, they might. I suppose this means that you may have to risk taking that call from the guy telling you that your computer is compromised and for a small fee, he can "fix it for you". Or it could be that Nigerian Prince wanting you to accept $1,000,000.00 from "the Royal family", and all you have to do is give him your bank account and routing numbers.
All I can tell you is that when my DS received the first one of these calls - it was from the actual MOC - from their cell phone, and that number was not obfuscated in any way. I told him, "you need to put that number in your contacts, buddy!"