Obviously you haven't read most of the complaints here. There is rarely a "live person" on the line. The caller just hangs up after a few seconds. Since you have done collections, you know how hard it is to get your target to answer the phone. It would be really stupid for a legit debt collector to drop 95% of its completed calls. But if you are just calling people at random and trying to get them to pay silly made-up charges, who cares if you ever reach the "right" person?
And your advice on cell phones is misleading. An automated call to your cell phone, from someone who you haven't given your phone number, is a sure sign of a scam. You can tell them that they can't call again, but if they didn't get your consent BEFORE the call then they have already broken the law.
It's an automatic dialer from a collection agency called "Mathews, Pierce & Lloyd." It doesn't matter if you don't owe the debt to which they are talking about and you tell them that who they are wanting isn't you and to not call anymore..they just do it again several times a day. Keep it up. I have my own "legal" ways and names on how to stop them from calling me again. I took one debt collector to court and won and I have NO problem taking another one to court.