The hook is free phone time. It can lure shoppers into stores and get them to spend more on their grocery bill, say retailers.
As prepaid phone cards have gained broad appeal, supermarkets have begun to look at the calling card as a customer reward or a way to add value to commodity purchases. Chains are tying them into their frequent-shopper programs, using them as giveaways to pull in traffic or as incentives and prizes in customer drawings.
Grand Union Co., Wayne, N.J., has