On Feb. 2, mapmaker Rand McNally launched a service called Rand McNally Traffic for $3.99 a month, available to most customers of AT&T Wireless, Sprint PCS and Verizon Wireless. At least three other companies offer similar services: MapQuest Traffic, from the MapQuest subsidiary of America Online, for $2.99 a month; Smart Traffic from Pharos Science & Applications, for $3.99 a month; and Vindigo Traffic from Vindigo Studios for $3.99 a month.Rand McNally Traffic puts highway maps on your phone's screen with color coding to show driving speed. You'll pay more than just the monthly fee, according to a report in the San Jose Mercury News. Verizon Wireless requires you to use airtime minutes to access traffic data; if you spend five minutes looking at highway maps, that's five minutes gone from your monthly bucket of minutes. Sprint PCS lets you use airtime minutes or subscribe to its unlimited PCS Vision data plan for $10 a month.Not all cell phones are compatible with these traffic services. As a rough rule of thumb, most phones with color screens that are less than 2 years old should work. Older phones, and those with black-and-white screens, often won't, the report said.The reporter reviewing the services said the expense and hassles of the two services outweighed the inconvenience of waiting 10 minutes for the next radio traffic report.Some wireless carriers also offer text-message updates on traffic conditions, covering the route of your choice at the time you specify; Verizon Wireless Traffic Alerts is one example. While the story said the current crop of cell phone traffic isn’t yet convenient, the future is brighter. New high-speed wireless phone data networks, rolling out in the next year or two, will instantly pop maps and updates into phones. Cell phones will soon know their geographic position, allowing them to display a traffic map at a precise location. Bluetooth short-range wireless networking could connect your phone to a bigger display screen in your car's dashboard, where maps would be displayed at an easily readable size, the report said.