IS THAT A PHONE OR A POCKET CALCULATOR?’’ IS the question many people will ask if you’ve got the Ericsson AF 738 cellular. This 5-ounce, 4-inch-high flip phone fits comfortably against your face, yet also provides 90 minutes of talk and 24 hours of standby on a single charge. Other slick design features: a backlit LCD panel, a menu-driven interface and side-mounted volume/menu scroll keys.