The Corner's Jonah Goldberg, noting that political organizations aren't covered by the Do Not Call Registry Law, says "it would in fact be worse if the government could block political speech because it's inconvenient" to the person receiving an unsolicited call. Let's put aside the Do Not Call Registry for a moment, and consider the real issue.
Remember door-to-door salesmen? (If you don't, you certainly don't remember bums.) Well, if you didn't want salesmen or bums knocking at your door, you would post a "No Soliciting" sign on your gate or at your front door. That would usually deflect unwanted callers (as we used to refer to people who came to the front door). If that didn't work, you would post a "No Trespassing" sign, which clearly meant "Don't come here without an invitation unless you're a postman, census taker, sheriff, police officer, or fireman."
Unsolicited phone calls are like door-to-door salesmen and bums. The callers have a right to call people who are willing to be called, but they don't have a right to call people who don't want to be called. It's my phone and my house, dammit. There's no free speech issue. Does freedom of speech give anyone the right to burst into your house at dinner time and shout "Joe Schmoe for dogcatcher!"? I don't think so.
Now, the only question is how to block those uninvited calls. The best way is to sign up for caller ID and buy a call bouncer, which blocks calls from designated numbers and diverts calls from other numbers to your answering machine unless you've flagged them as "acceptable." Calls from acceptable numbers will ring longer before going to the answering machine. That gives you a chance to pick up if you're there and want to do so. (The setup also allows you to screen your calls and avoid long-winded conversations with friends and family when you don't have time for such conversations.) The technology works and it's cheap.
The Do Not Call Registry is just another pseudo-panacea. It's a "gift" from the same people who gave you the McCain-Feingold Act.