Long-distance credit cards have been with us as long as "plastic" itself has, offering convenience and a way to record employees' phone habits. Now come long-distance debit cards, offering convenience and a way to record employees' phone habits. The difference: with a debit card, you must have money in an account with the long-distance vendor before you place the call. (In one clever variation of the prepayment setup, a business can give away debit cards as premiums.)

The quid pro quo for advance payment is savings. Capital Telecommunications (CTI), a regional long-distance provider serving eight northeastern states as well as Texas and the District of Columbia, claims the rates for daytime calls placed through its Upfront debit card beat "big three" standard rates by substantial amounts. Typical credit-card costs for a one-minute daytime call from New York City to Los Angeles are $1.05 for AT&T, $1 for Sprint, and 99¢ for MCI; CTI's debit-card charge is only 30¢. The savings curve flattens on lengthier conversations; for 20 minutes, the respective costs are $5.80, $5.75, and $5.55. CTI's $4.10 is a good 26% lower. When the money runs out, so does use of the card. Usually, a customer replenishes the account by check. But, in an odd conflict of concept, debit-card vendors will accept payment from credit merchants Visa or MasterCard.

Hardly had the debit calling card hit the street when so did a popularized variety -- the owned card. Introduced in Europe in 1976, fixed-value calling cards weren't sold in the United States until last year, when the concept was marketed by both U.S. Fiber, a New York City company founded for the purpose, and Western Union. As opposed to most credit and debit cards, which carry privileged billing information embedded in a magnetized stripe and which can be used without limit at specially equipped pay phones, U.S. Fiber's prepaid calling card is limited to denominations of $5, $10, $20, and $50. The ducats are sold through dealers such as newsstands and gas stations. The buyer calls an 800 number from any site, punches in the card's unique 10-digit code, and places a call. The vendor's computer monitors the activity and subtracts the charge from the card's face value. (If, say, a $2.80 call is placed using a $10 card, only $7.20 will be available on that card for the next call.)

As with a debit card, calls are billed at flat rates. U.S. Fiber's Talk Ticket charges 50¢ a minute for a domestic call to any place in the country, including Alaska and Hawaii. A company with a slew of employees on the road can regulate budgets by handing out prepaid cards in denominations that put a ceiling on phone use. Cards in any denomination are available in bulk for a company to use as premiums. (The company's ad can be printed on one side.) U.S. Fiber backs up such campaigns by leasing 800 numbers that will recite a business's sales spiel before allowing the card's recipient to place a call.

For information on CTI's Upfront calling card, call 800-888-3510; on Talk Ticket from U.S. Fiber, 914-833-3800; on Phone Card from Western Union, 800-374-0909.

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