The days when a phone was simply used to place calls are long gone. (A study last year noted calling is one of the last things we do with smartphones, ranking far behind activities like web browsing and social networking.) But odds are most people don't think of their smartphones as tracking devices.
Smartphones as Tracking Devices
Smartphones with Wi-Fi enabled periodically transmit Wi-Fi messages, even when not associated to a network. That makes them excellent devices for tracking your shopping route, a fact that has not gone unnoticed by retailers and malls.
Tracking systems can identify individual shoppers by monitoring one of two things: a phone’s International Mobile Subscriber Identity number (The number constantly transmitted from all cell phones to their service providers. However, to reduce eavesdroppers, the IMSI is sent as rarely as possible and a randomly-generated TMSI is sent instead.) or the Media Access Control (MAC) address (transmitted when the device’s Wi-Fi is enabled, which is the default setting on most devices).
But it goes deeper. In a paper published last month in the International Symposium on Research in Grey-Hat Hacking, researcher Mathieu Cunche noted that the MAC address of the devices could be collected and used to uniquely identify mobile devices. He continued:
A device with a Wi-Fi interface turned-on acts as an actual wireless beacon by periodically advertising in clear a unique identifier. This is also true for other technologies such as GSM and Bluetooth that periodically send in clear a unique identifier (MAC address for Bluetooth and TMSI for the GSM) … Thanks to those wireless beacons that we are carrying in our pockets, Radio Frequency (RF) tracking is now possible."
In London, a company called Renew programmed "smart" trash bins to record the unique addresses of smartphones carried by pedestrians. People were unnerved, Bryan Pearson, CEO of Loyalty One, wrote in a blog post:
No one was notified, and there was no way for people to know that their personal data was being collected. But in one day, a small number of those bins collected data from more than a million devices. Renew since discontinued the tracking, but that won’t stop the technology."
More and more retailers, from Nordstrom and Benetton to Family Dollar and Cabela's, are experimenting with technology that lets them track customers' movements by their cellphones as they make their way through their stores.
In theory, the in-store tracking isn't much different than the data mining online retailers do with shoppers' search and spending habits. The only difference: Instead of analyzing keystrokes and search history, some brick and mortar retailers monitor shoppers' moves throughout the store by following their smartphones' Wi-Fi signals.