Pay By the Day
Price is another differentiator: The least-expensive dedicated GPS devices cost about $200, with midrange models going for $350 to $400. Cell phone navigation services typically cost about $10 a month; some are available on a daily basis. You can get Verizon's VZ Navigator for $3 a day, for example.
Many mobile phones use what is called assisted GPS, which combines cell-signal triangulation and GPS to establish your location when you first turn them on, thereby speeding startup. By contrast, phones that use autonomous GPS must acquire at least three separate GPS signals to determine your bearings, which can take several minutes. Of the major carriers offering GPS services, only Sprint and Verizon have assisted GPS; Cingular, which has been relatively slow to adopt GPS, uses only autonomous service.
Navigation services on handsets aren't new, but they have acquired new features. TeleNav, for example, now lets you check traffic on your route every 5 minutes via automatic calls to the Inrix.com traffic service. When the service detects a snarl, it generates both voice and on-screen alerts. You can then calculate a different route or continue on your current one; in either case, TeleNav adjusts your estimated arrival time accordingly.
TeleNav and the latest release of competitor Telmap offer both pedestrian and driving directions. Telmap Navigator 3 also lets you search for businesses near your current location, around other locations, or near address book entries. The Telmap service is currently available in the United States only through Sprint/Nextel (under the AOL/MapQuest Navigator brand). TeleNav offers its navigation services directly (for supported devices) for $10 a month or $199 for two years.
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