Data mining. That's not (currently) illegal.
A buddy of mine worked for a cell phone company. He told me that he could sit at his desk and pull up anyone's cell phone records and see the numbers they called, what towers were handling the call, and how long they talked. Those companies could sell that data if they choose to do so.
I asked him if they also recorded the conversation. He said they did not -- as far as he knew -- but he said it wouldn't be difficult. It's not difficult to do, just too expensive to store. Of course, storage media is getting cheaper and cheaper.
Direct marketers don't have powers of arrest, last I checked. That is the key difference.