You’ve seen cell phone ads trumpeting "GPS enabled," or maybe your phone already has GPS built into its many features. You may have wondered what GPS is, why it is attracting interest, or - more to the point - what can GPS do for you in your home or business?

What Is It?
First of all, GPS is the acronym for Global Positioning System. The actual system is a constellation of 27 satellites (24 in full operation plus three others to be used if one or more of the others fail) that orbit the earth. The U.S. military originally developed and installed this satellite network as a military navigation system, but now it is open to everyone. A GPS receiver locates four or more of these satellites, determines the distance to each, and uses this data to figure out its own location. This calculation is based on a mathematical principle called trilateration. The process is complicated to explain, but it is easy to see how GPS can be used to benefit cell phone users.

What Can It Do?
Simply stated, a GPS-enabled phone, hooked up with the appropriate provider of cellular data, can be both a navigational and a tracking tool. It can provide directions to help you find your way in unfamiliar territory, and can be used to locate and track family members or employees in the field. We can thank the FCC and its mandate - known as Enhanced (or E) 911 - requiring carriers to be able to locate emergency cell phone calls by the end of 2005 - for spurring private enterprise to develop a host of other GPS-based services for location-aware handsets. Here are some of the offerings available now:

Product	Features
TeleNav- available for many Motorola’s GPS-enabled handset models- from Nextel Costs: $6-10 per month and requires Nextel’s data service.	Navigation with 2 options: plan ahead on TeleNav Web site, or call TeleNav for turn-by-turn directions, which are spoken over the handset’s speaker. No map display but phone shows direction of turns and distances.
Gpmobile advanced handset- based tracking service from Gpware is compatible with several Nokia Series 60 phones and Sony Ericsson P800 and P900. Operates with many networks including AT&T, Cingular and T-Mobile. Costs: $15 per month with a set-up fee of $25.	Advanced navigation assistance. Directions are spoken turn-by-turn with visual prompts displayed on the phone. Shows more detail of upcoming junctions and intersections. Can’t use integrated GPS chips to access data but Gpware offers a Bluetooth receiver to work with phones it supports. Gpware plans to expand services to include points-of-interest, directory services, tracking, mobile-to-mobile location features, and local traffic alerts.
Ulocate Tracking Services (for family use) for Motorola (i730, i88s and i58sr) from Nextel. Password-protected family account allows users to see where everyone is headed (and their speed) Costs $11.00 monthly to track 1 phone and another $8.00 for each additional one.	Phones registered with Ulocate can be tracked. Location is viewed on another handset or a web page. Coming soon: users will be able to navigate to another phone’s location. Privacy issue: users can shut down monitoring software on the handset
AtlasTruck from Networks in Motion for Nextel phones Contact supplier for cost information.	Enables small businesses to use Nextel phones to track and route employees, and to check up on pick-up and delivery of goods. Costs less than installing traditional GPS "black boxes" on commercial vehicles.

Bright Future
The next generation of GPS-based services offers some exciting further options. The idea is to use the cell phone to download data constantly to provide location-specific information, like local road or driving conditions, or to pull up local service directories to show you where nearby restaurants, churches or shopping malls are located. Today, the Location-Based Services (or LBS) available in the U.S. are limited to the basic options outlined above, but that will probably change fast. LBS options have taken flight in Asia, and all the major American carriers know it.

Though most potential providers of LBS are tight-lipped about their plans, industry analysts believe that Sprint, Verizon Wireless, and other big names all have GPS-based offerings under development. Industry experts wonder if the direction cell phones are headed doesn’t signal trouble ahead for the PDA industry. They predict that the increasing demand for "smart" cell phones will take a chunk out of the PDA market. Others feel that handsets won’t have the speed or sufficient screen size to be a real threat.

Whatever happens, GPS-enabled phones are here, and their future looks bright.