The telephone system in the United States is designed so that landline is tied to a certain address. This was implemented so that if someone dials 911 during an emergency the operator can give dispatch the address from which the all was made even if the person making the call is unable to provide it. With the invention and popularization of cell phones, this system was put in jeopardy. No longer was the location of a caller tied to their phone, and thusly, the operator could not always obtain an address.
During the events of September 11th, it became clear that a better emergency response system could be set up if the location of a cell phone user calling for help could be recovered. After 2005, most major wireless providers began building technology into their headsets that allowed 911 dispatchers to locate those who needed assistance.
Today, a majority of providers use the GSM or Global System for Mobile communications to give service to their customers. This systems allows users of all wireless phone companies to utilize the signal towers or call users outside of their network operators. Because of this arrangement, most cell phones can make calls in any part of the country or the world through roaming. It also connects every cell phone user to one another and makes it possible to call those outside of a given network. Under this system, every phone is given an identity which ties it to its user. Since the network knows the identity of the phone it is possible to find the location of it in a number of ways.
When a user makes a phone call, a signal is sent to local signal towers in order to transmit the message where it needs to go. Techniques for locating the user of a cell phone are in part based on this principle. The handset and the computers running the network can confer on which tower the handset communicates with, the signal strength, the strength of nearby phones, and the relationship of the phone to other towers in order to calculate the relative location of the handset. This is why the identity of a cell phone is so important. If the network recognizes the phone, it can be used to determine where the phone is being used.
However, since this technology is not perfect, and a handset is most effectively located only when it is being used to make a call, many phones today are also equipped with GPS. The Global Positioning Systems uses a receiver and signals from satellites in order to track the movement of the receiver on the earth. While most phones contain something approximating this technology, some are sold with GPS navigation features or tracking abilities. These allow the phone to retrieve directions as it is traveling based on its location or tells parents the locations of their children. Though these features might not be part of a basic phones, the ability to receive GPS signals in present in most handsets.
Through the use of these technologies, an emergency dispatcher can be given the coordinates of a caller almost as if they were calling from a landline. Though the system is still not set up perfectly, a hybridization of both of these methods will also yield the location of the cell phone user. It is important to note that emergency call centers and the cell phone providers are the only ones with access to this information. However, the owner of a cell phone with certain capabilities can allow others to view this data.
Laws to create this system pinpointing the bearings of handsets were established for situations of abduction, hijacking, or if the caller is injured or unaware of where they are. Its implementation can make it easier to save lives and increases the safety of wireless users.
