Did anything change with "phone spammers"?

Several years ago, between 2006 and 2008, I was constantly getting unsolicited calls on my cell phone. I would estimate that I got an average of one a day, but sometimes I'd get several in one day. They were primarily either robocalls from shady refinance companies, vehicle warranty scamsters or there was simply dead air when I picked up the phone, so I don't know what they were. I assumed that I was on a list since I owned my own business. It became enough of a time waster that I purchased a piece of software for my phone that sent everything to voice mail unless it was in my address book. This was when I was still using a Treo 680 which now looks like a TRS-80 next to my iPhone, and the software was developed by a dude who pretty much disappeared. So updates and support were out of the question. I wondered what was going to happen when I had to switch phones.

Now I get unwanted phone calls about twice a month, and sometimes I'll go several months without any. I doubt anything happened with laws because these people don't obey them anyway. Maybe it's just the business downturn and credit crunch that has dried up the activity of these folks, but I have a hard time believing that this could account for such a drastic decline. Maybe my carrier has cracked down on these people? There are good sites where you can log annoying calls: whocallsme.com, phoneowner.info, 800notes.com, whocalledus.com, etc. Having these sites on the 'net has allowed people to basically search for numbers and have information concerning the nature of the calls. I don't know how much this helps the shutting down of "phone spammers", but I don't suppose they like it much.