Getting content delivered to mobile phones is all the rage lately, and GPS navigation is no exception. Ask anyone in the business and they’ll tell you cell phones are the next major growth area for satellite navigation.  Given the number of cell phones already in circulation, utilizing the existing cell phone infrastructure for GPS navigation seems like a logical next step.

For $9.95/month TeleNav offers turn-by-turn navigation with voice guidance (including text-to-speech),  full mapping coverage of the United States, and a huge Points of Interest (POI) database with more than 10 million entries. Note that you'll also need to have a data plan from your provider.

Sounds great , doesn’t it? So how does cell-phone based navigation compare to dedicated GPS devices? This month I test out TeleNav’s Navigator application and compare how the service measures up.

Features

• Turn-by-turn navigation
• Voice guidance with text-to-speech
• Automatic re-route if you miss a turn
• 2D and 3D moving maps
• Route Preview
• Biz Finder application with over 10 million points of interest
• Fuel Finder to locate the lowest gas prices in town
• Full-color maps in the U.S.
• Walking mode for using TeleNav on foot

Specification

Unlike traditional GPS devices which rely solely on GPS signals to operate, TeleNav's Navigator application also relies on cellular reception. This may or may not be an issue, depending where you live; in areas where cell reception is either unreliable or non-existent, relying on cell phone reception for navigation may be impractical.

One statistic you'll notice right away is TeleNav's claim that Navigator includes over 10 million points of interest in its POI database. That's almost double the number that even the most expensive dedicated GPS has. Unlike a traditional GPS which stores the entire POI database locally, TeleNav uses the cell phone's data capabilities to perform POI lookups over the network, removing the local storage size limitations while also making it possible to ensure that the POI database is always up-to-date. It's worth noting, however, that POIs can only be searched when you have cell reception.

Mounting in the Car

Thankfully, TeleNav included a universal cell phone mount with the unit they sent me for evaluation. If you're considering using your cell phone for navigation in the car, you should consider the mount absolutely essential. With a little Internet searching, you can pick up one of these mounts for under $20 -- money well spent if you plan on using the cell phone for GPS.

This mount is a generic cell phone mount that can be adjusted to hold most phones. To attach the mount to your windshield, you press the suction cup against the glass and raise the lever to lock the mount into place.

Once the Flex-Arm is articulated into the desired position, insert the cell phone into the mount. TeleNav sent me the Sprint Katana cell phone by Sanyo, shown above, with TeleNav's GPS Navigator application pre-installed.

Here we see the mount attached to the windshield, and the cell phone attached to the mount and powered on.

Screen Size and Brightness

Compared to the Garmin nuvi's beautiful, bright, wide display, the Sprint Katana looks small and dim. Screen size was my second biggest complaint when navigating with TeleNav (my biggest gripe was the reliance on cell phone reception -- more on that later). I found the map too small and difficult to read. To be fair, this was more an issue with the cell phone rather than TeleNav's software. Still, most cell phones have similarly sized displays, so this would have been an issue on any phone, and therefore a valid complaint about using your cell phone as an in-car GPS in general.

Text-to-Speech and Speaker Quality

Text-to-speech technology makes it possible for your GPS to announce not only the direction of the next maneuver, but also to announce the actual street/highway name of the next maneuver (e.g. "Turn left onto I-195 North towards Providence"). Text-to-speech on TeleNav's Navigator was acceptable, though not outstanding. The voice was clear enough that you could understand the instruction, but still sounded like a computerized voice. Relative to other GPS devices, I found TeleNav's voice similar in quality to magellan's text-to-speech translation quality. Overall, TomTom seems to have the best text-to-speech, followed by Garmin, with Magellan in third place.

Another issue I had when using TeleNav's Navigator was that I consistently found the phone's built-in speakerphone not loud enough to hear the navigation prompts. I had to repeat the command multiple times before I could understand what was being said. Cell phones tend to have poor quality speakerphones that distort and sound tinny at high volumes. The Blackberry speakerphone tends to be better than most, but at highway speeds even the Blackberry speakerphone is hard to hear.