The reason? TeleNav, a Java software program for the phones. Once you tell the program where you want to go, it reads your position using GPS and then downloads instructions. Included are icons for each turn (giving you a rough idea of the turn's degree, sharp or gradual), plus, if you choose, phonetic readings of the street names — you actually hear "Turn left onto the Dutchess Turnpike," for instance.

The directions you get are worthwhile. Though you can't choose between shortest distance and shortest time like many full-fledged systems, the route chosen is generally the quickest. There's no map, but if you pay attention to the distance it shows on screen, plus the street signs along the road, you get the hang of it pretty well. Think of it as someone sitting shotgun, reading from a map. A true sign of usability is how fast the system recalculates a route if you've strayed from the prescribed path, and I was surprised at how fast TeleNav did that.

There's one big problem with TeleNav: its reliance on cellular coverage. Even though it can get you to any destination regardless of coverage, it needs to be able to talk to the network in order to download navigation information. It can steer you into the wilderness with no problem, but you better remember how to get back out because this won't be able to help you.

TeleNav isn't be meant to take the place of the $1,000-and-up portable navigation systems for cars. Still, as a source of instant, real-time navigation — built right into a product you're already carrying around with you — it could really bail you out of a jam. As long as you're in its coverage area.