Keep a pad of paper next to the phone. When a Telemarketer calls you, they are required by law to give you their name, who they are representing and where they are calling from. Many conveniently forget to give you this information, so feel free to ask for it. Write it down, along with the date, time, and any other comments that will help you recall the phone call.

When trying to get information out of them, it's best not to be confrontational. Remember, they are rewarded for each person who accepts what they're selling, even if it's just to get you to confirm your address. Don't give them what they want, but give them a reason to think that they might get it--you're just unsure that they are a "legitimate" telemarketer.

For example, I often say, "Before I give you my address or agree to accept your information, I'd like to know that you actually represent [Brand X], and you're not just posing as them in order to get my information? I've heard of people posing as telemarketing companies to get personal information on people, and then they use the information illegally."

If you play dumb and friendly, they often fall all over themselves to prove their legitimacy. Most often they supply you with an 800 number to the company's customer service department, but sometimes they divulge a tracking number. THAT'S golden!

The next piece of information you want is the name of the telemarketing firm itself. Few companies do their own telemarketing, even if the victims are a list of its own customers. Ask the person calling if they actually work for the bank/service they are representing, or if they work for a telemarketing firm. At this point, most telemarketers realize they won't get the carrot, but they're engaged. Most will try to salvage the call or exit gracefully, but if you're persistent and polite you can get the name of the company out of them.

Try a segue from the proof of legitimacy to the telemarketing firm something like:
      [Telemarketer]: ...and you can call 800-888-8888 to confirm all this.
      [You]: Oh. I see. Thanks. I'll call them when we get done. So do you actually work for [Brand X], or do you work for a telemarketing firm?

That question always throws them. Some try and hide the fact. But legally, they have to give the information up. At this point they're almost always smart enough to figure out what you're up to, so after you get their firm's name you can move to the most important part:

This is why you want the telemarketing firm's name as well--you can kill two vultures with one stone. A firm called Convergys, for example, called me on behalf of both MCI and Ameritech. Since I was only called once by MCI and once by Ameritech, I couldn't attack them. But I asked to be put on Convergys's Do Not Call List both times, so I've got a case against Convergys.

Note: You must be specific when you tell them that you don't wish to receive a call again. You must specify that you want your number placed on a "Do Not Call List." If you just say "Take me off your list" they can pretend like they didn't know what you meant, so they have the excuse that they thought you wanted to be taken off the Do Not Call List. It sounds silly, but I've heard much sillier defenses from legal departments, so you might as well nip this one in the bud.

Record all this information and anything else that will help you remember the call. Save it. They probably won't call you again (at least not under the same name). But every once in a while you'll find a company that doesn't care or is sloppy. After a few months, the sloppy company will make the repeat call. Treat it like any other telemarketing call. Remember, this operator has no idea of your history. If their previous call was within 12 months, you're ready to stick it to them!