Coupa Cafe in downtown Palo Alto is a popular hangout with Stanford students and techies. So it’s no surprise that they offer free Wi-Fi. 

But when I get to my table, turn on my phone and open my browser, it takes me to Facebook. It instructs me to log in to get free Wi-Fi.  (You can bypass the sign-in but that wasn’t totally apparent to me.)

Facebook says its experimenting with a few local businesses to “offer a quick and easy way to access free Wi-Fi after checking in on Facebook.”

Rocky Agrawal, a consultant at reDesign mobile, suspects there’s more to this than good will.

“It’s a good way for Facebook to know where you’re at, they can deliver all sorts of new offers,” Agrawal says.

Companies are banking on location based advertising to bring in big money for mobile, but there are a lot of hurdles to clear before companies like Facebook can target your location precisely.

Matthew Groves created the app “Dude, Where’s My Car.” It relies on GPS and that can be problematic.

“It all depends on where you’re at, are you in a parking lot, are you around tall buildings or trees, basically do you have a clear view of the sky,” Groves says.  

Using location data from cell towers is another option, but Groves says that’s less accurate because there aren’t enough of them. To get around that problem, he says companies like Google are testing their own Wi-Fi hotspots, which offer free Internet.

As for Facebook, it gave the Coupa a wireless router, which can be tied to a location. Argawal says, you can imagine tech companies like Facebook sending out routers to millions of businesses.

“So all of the sudden you have precise locations on every business you’ve shipped that too,” Agrawal says.

And so one day soon, someone like me could get an offer for a free smoothie to go with my ham sandwich.