Location-based service

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Location-based services (LBS) are offered by some cell phone networks as a way to send custom advertising and other information to cell-phone subscribers based on their current location. The cell-phone service provider gets the location from a GPS chip built into the phone, or using radiolocation and trilateration based on the signal-strength of the closest cell-phone towers (for phones without GPS features). In the UK, networks do not use trilateration; LBS services use a single base station, with a 'radius' of inaccuracy, to determine a phone's location.

One example of a location-based service might be to allow the subscriber to find the nearest business of a certain type, such as an Italian restaurant. The ability of the restaurant to send an invitation to bypassers has also been mentioned, even though this might be regarded as unsolicited commercial email or spamming. These services were launched in the late 1990s, and (as of 2004) the development in this area seems to be driven more by technical ability than by user need.

With the passing of the Can Spam Act in 2005, it became illegal in the United States to send any message to the end user without the end user specifically opting-in. This put an additional challenge on LBS applications as far as 'carrier-centric' services were concerned. As a result, there has been a focus on user-centric location-based services and applications which give the user control of the experience, typically by opting in first via a website or mobile interface (such as SMS, mobile Web, and Java/BREW applications).

In the U.S. the FCC requires that all carriers meet certain criteria for supporting location-based services (FCC 94-102). The mandate requires 95% of handsets resolve within 300 meters for network-based tracking (e.g. triangulation) and 150 meters for handset-based tracking (e.g. GPS). This can be especially useful when dialing an emergency telephone number - such as enhanced 9-1-1 in North America, or 112 in Europe - so that the operator can dispatch emergency services such as Emergency Medical Services, police or firefighters to the correct location.

One implication of this technology is that data about a subscriber's location and historical movements is owned and controlled by the network operator. Revelations that the US government maintains a massive database of all domestic phone calls suggests that a permanent log of the location of every cell phone may be collected as well.