Cringing at the attempt at such warm and fuzzy customer service, I nevertheless logged in. And now that growing numbers of card issuers are now providing free FICO scores — actual FICO scores, not FICO-like ones — I encourage you to see if you can get yours, too.

Why Credit Scores Matter

That’s because this three-digit number (typically ranging from 300 to 850) plays a big role in whether you’re approved for a mortgage, auto loan, home equity line, business loan or credit card — and the interest rate you’ll pay. (In general, the higher your credit score, the lower your rate.)

Now, let me tell you why it’s becoming easier to get a free FICO score, the benefit of knowing that number versus another credit score and, most important, how to boost your score once you learn what it is.

MORE: The Truth About Those Free Credit Scores

Click here to: Read on Forbes.

Nearly two years ago, the Consumer Financial Protection Bureau (CFPB) called on the nation’s top credit card issuers to make credit scores freely available. FICO, a division of the Fair Isaac Corp. (the company behind FICO scores), had already launched the FICO Score Open Access program to make it easier for them to do so.

Who’s Truly Offering Free FICO Scores

Slowly, big-name card issuers have been offering FICO scores gratis to some of their customers. In addition to Citibank, they include American Express, Bank of America, Barclays, Chase and Discover. Some banks make free FICO scores available to their checking account customers, too. Today, holders of 100 million accounts in the U.S. have regular access to FICO scores for free, up from 8 million two years ago, according to Jim Wehmann, FICO’s executive vice president, Scores.

To order a credit score from FICO directly, by contrast, you’d have to pay $19.95 for one, which would come with a credit report from one of the big three credit bureaus: Transunion, Equifax or Experian.

But, you may be saying, haven’t some consumer credit sites likeCreditKarma.com, Credit.com, CreditSesame.com and Quizzle.com been offering free scores for years? Well, yes, but not free FICO scores and that’s a difference with a distinction. The reason: “FICO is the most commonly used credit scoring model,” says Michael Schreiber, editor-in-chief of Credit.com.

MORE: Secret Numbers As Important As Your Credit Score

The Funny Thing About FICO

Now, onto FICO scores themselves and how to boost yours.

The national average FICO score is now 695 — the highest it’s been in at least a decade, according to Fair Isaac. That’s a good sign for the U.S. economy and the public’s finances. Better yet, nearly 20 percent of consumers today have FICO scores above 800. Impressive.

But here’s where things get messy: The new free FICO scores aren’t identical from one card issuer to another. In other words, if you asked for your FICO score from, say, Citi and Discover, odds are you’d get two different numbers.

“There are dozens of types of FICO scores, which is why the FICO score that you’re seeing from one bank may be different from the FICO score you’re getting from another,” says Schreiber.

Each card issuer offering free FICO scores is partnering with just one of the credit bureaus and each bureau uses a somewhat different formula for arriving at a number.

In my case, Citi uses data from Equifax with what’s called a “Bankcard Score 8 model.” And, wouldn’t you know it, this FICO score doesn’t use the standard 300 to 850 range but 250 to 900. If you carry a Chase Slate card, you get access to a FICO score based on data from Experian, according to Rob Berger, a Forbes contributor who also runs the personal-finance web site Dough Roller. American Express cardholders get the privilege of FICO scores based on Experian data, too. Discover goes with TransUnion.

Nevertheless, the card companies use similar criteria to gauge creditworthiness when calculating their scores — from your payment history to the amount of available credit you have available.

4 Ways to Raise Your FICO Score

There’s no magic formula for ramping up your credit score, and boosting your number can’t be done over night. That said, it is possible to raise your score in a few months with these four moves:

1. Pay your bills on time. This is the No. 1 thing you can do to boost your credit score. Payment history accounts for 35 percent of a FICO score. So pay every card on time, every month.

2. Double-up payments. The second-largest factor affecting a FICO score, accounting for 30 percent of the equation, is the amount you owe. So consider making two payments on your card in a given month if you’re applying for credit. The balance used for your credit score is typically the last statement balance and people who run up a high balance on a single card may be punished — even if they pay that balance off in full each month.

In other words, if you have $25,000 in credit available on three cards and owe a balance of $5,000 apiece on two of them during the month before paying them off, and a credit issuer pulls your credit score before the payment date, it may look like you’re wildly tapping your available credit. Your score is, after all, a snapshot of a moment in time. It doesn’t factor in that your balance is paid in full each month; it’s the amount you owe right at that moment.

3. Keep your oldest credit card account open. That’s because the length of your credit history accounts for 15 percent of your FICO score.

It can be tempting to jettison an old card you quit using because, say, it doesn’t help you with frequent flier miles. But closing an account can shrink your total amount of available credit. Then, if you carry a balance on your other cards, the move will increase your credit utilization rate and lower your credit score.

4. Review your credit report. One of the biggest factors influencing your credit score could be a mistake on your credit report, including out-of-date information. Some 25 percent of consumers have mistakes on their credit reports that could affect their scores, according to Forbes’ Laura Shin.

To check on the accuracy of your credit reports, go to AnnualCreditReport.comevery 12 months to request a free credit report from Experian, Equifax and TransUnion. Your credit score won’t be included. But the credit bureaus will be happy to sell it to you — and that can get costly. At Experian, for instance, the seven-day trial membership for its $1 Credit Report & FICO Score can quickly turn into a $21.95 monthly fee unless you cancel before the trial ends.

Should you have disputes about your report, you’ll normally need to work with the individual credit agencies. That can be a slog: Errors can take up to six months to get fixed, assuming you get satisfaction. CreditKarma,  however, now lets its users file disputes from within its site for free through Direct Dispute. That’s good, Karma.