[duskwuff]

This is only effective against the relatively honest telemarketers that use correct Caller ID information. The really bad ones, like the one involved in this article, use spoofed Caller ID -- reporting them to the FTC is a waste of time for everyone involved.

[MichaelGG]

It wouldn't be if anyone actually followed through on the complaint. Each company knows who sent them the call, even if the caller ID is misleading. (Though you might have to keep digging though several companies to find the actual call sender.)