"Your phone number, please?"

Your eyes dart around. Your palms get sweaty. You feel vulnerable. If you had just met the love of your life or had just caught up with a childhood friend that you hadn't seen in ages, this would have seemed like an appropriate query.

Unfortunately, that's not the case this time. You are wedged at the head of a long checkout line and you know absolutely nothing about the cashier lobbing the question your way. But the lack of familiarity isn't mutual. The retailer knows a lot more about you than you think. Your phone number linked to your buying patterns is gold in enterprising, merchandising hands. You still want my phone number? Not until you buy me breakfast, snookums.  

The art of the deal
Checking out of a store shouldn't be a trying experience. You have something that you want to buy. The retail establishment clearly wants to sell it to you. The price is agreed upon by your willingness to lug it over to the cashier. Shouldn't there be less barriers getting in the way of closing the transaction? In theory, sure. But there is a hidden markup in the mix. It's called information. Knowing your identity -- or, at the very least, knowing your ZIP code -- will help the company's marketing efficiency. 

RadioShack (NYSE: RSH) was an early arrival to the telephonic inquisition. Yes, the same company sporting the "You've got questions, we've got answers" jingle once had a beefy question for you. That phone number, again?

But shoppers didn't bargain on opening up to the company just to pick up a pair of fresh batteries. Perhaps that's why the 7,000-unit consumer electronics chain gave up on the practice two years ago. However, new retailers are rising from the RadioShack's marketing research ashes.

Popular chains like Toys "R" Us(NYSE: TOY), Linens 'n Things(NYSE: LIN), and Best Buy(NYSE: BBY) have taken a shot at asking patrons for either their ZIP code or their phone number. Mined over matter, the Better Business Bureau isn't about to condemn the practice, but it won't stop the complaints from pouring in. It's invasive. Is it really necessary?

Mined over matter
Clark Howard, the host of a consumer action radio show in Atlanta, Ga., recently tackled the growing trend of info-hungry retailers. It spawned an active thread on our own animated consumer credit discussion board. While noting that ZIP codes are now being used to help authorize credit card transactions, that doesn't explain why I've been asked the same thing even as my outstretched hand is holding greenbacks.

Am I setting up my neighbors to be junk-targeted for the retailer's next mass mailing? Am I hurting my chances of securing a location closer to my home if the parent company thinks the expansion may cannibalize existing locations? Are frustrated shoppers willing to fudge, assuring that the tony 90210 district in Beverly Hills will be up to their Hummers and toy poodles in spam?

When the object of your market research affection becomes defiant doesn't it all just flat-out fall apart? The only thing worse than a lack of information is a plethora of wrong information. What are you left with? ZIP.

Yet telephone numbers are clearly even more invasive. That's an open admission. That's you raising your hand to say "here" when a marketer takes roll. While it can be argued that circling the bull's-eye to your home can be a positive if it means that you will be receiving special discount mailings from retailers you frequent geared towards products you typically purchase, when exactly did you sign off on the retailer's privacy policy?

Asking for phone numbers and ZIP codes? That's just wrong. Try earning that trust. Don't take the customer out of the customer service. So, are you still here asking me for my phone number? Can I scribble it on a cocktail napkin for you? Ha! I'm just teasing you, sweetie. I'm sorry. I'm just not that easy. You haven't even met my parents! Oh, that's right. You have. You know everything about them.  


Five Ways Out
So what will you do the next time that a persistent cashier asks you for your phone number? Will you give in? Here are five suggestions to keep you from blurting out the seven numbers that are dear to you.

1. Tell the sales clerk that your number is unlisted. If you are told that it is for security reasons, take them to task. While some credit card companies will use billing zip codes to verify transactions, there isn't a single one that will demand your phone number. Flash some other form of ID to the cashier.

2. If your concern isn't so much the retailer knowing who you are, but rather some unsavory characters behind you memorizing your phone number, just jot it down and hand it over to the cashier. If you have a business card, that will probably do.

3. Your area code followed by 555-1212 isn't a complete fib. It is the number for directory assistance. If your number were listed it would be one way to reach you.

4. Refuse on principle. Do you really think that they will turn away the sale? It's a more honest approach than just making up a number like 867-5309.

5. Give them the store's phone number. After all, that is where they can reach you at the moment, right?

Longtime Fool contributor Rick Aristotle Munarriz hates giving out his phone number, and he's never found a cashier willing to spring for breakfast. He does own shares in Netflix. Rick's stock holdings can be viewed online, as can the Fool's disclosure policy.