Brring!

Brring is a free service for US residents which gives you a private, local second phone number to use in place of your primary phone. Any calls to this number forward to your primary phone, but only after playing a short advertisement (10 seconds or less). This short ad will deter about 90% of all pesky telemarketers and they will hang up before the call comes through and rings on your phone.

It's not only free, you actually make money... if they pay you, that is.
Brring pays its users for referring new members and for profiling their friends to specify what types of ads they would like to hear (earnings details). Although they had previously paid money for each call ($1 for each of the first 10 calls, $.05 per call after that), they have discontinued these earnings due to funding issues.

Do not use Brring with high hopes of getting paid, it is privately funded and for whatever reason they are collecting no money from their advertisers while their product is still in development stages. Conditions may improve in the future, no one knows for sure.

Simply click on the Brring logo above to sign up!

Using Brring
This guide assumes that you are using Brring as an alternative phone number to reduce annoying telemarketer calls while completing offers online, although if you want your friends to call your Brring number that's fine too!

First and foremost, after creating your new Brring account (sign up here), go to the "Earn More Rewards" page and select "Set ad playing rules." Move the ad frequency slider to "Always" to ensure that every caller hears an ad. If you skip this step, you are guaranteed to hear more telemarketing calls ringing your primary phone.

Your Brring number is ready to go! If you call it from your own phone, you can check your balance and record audio clips of your name and invite greeting. If the next paragraph interests you, you can upload the MP3 ringback tone by going to "My Ringback."

The mouse trap to all annoying telemarketers, ringback tones!
Brring allows you to upload an MP3 file as a ringback tone which is played while Brring connects the caller to your phone. My suggestion if you want telemarketers to hang up right away is to use a busy signal!

Results
Of the 220 calls I received to my Brring number in the first two months, approximately 25 of the callers stayed on the line long enough to make my phone ring. Of those 25, less than 10 stayed on the line long enough to make the phone ring a second time (because they heard my busy signal ringback tone). Of those 10, I answered about 5 because I wasn't sure if it was someone I knew or not.

National Do Not Call Registry

Many Americans, when considering how to stop telemarketers, think of the Do Not Call Registry (donotcall.gov). This is a great way to curb annoying calls from companies you've never heard of which seem to pull your number out of the ether (aka unsolicited calls).

However, when you're earning points online by completing offers, you are submitting your phone number directly to advertisers. You are soliciting their calls. Therefore, by agreeing to the terms of many of these offers, you are giving the advertiser express permission to use (and sometimes even distribute) your phone number. The calls directly relating to these offers are not bound by the Do Not Call list.

Here is a direct quote from the Terms of Use of one of the advertisers:
"By clicking on the Continue above I am requesting to be contacted by I Can Print Photos.com's offer sponsors and marketing partners regardless of any DNC List registration."