Mobile phone tracking

Mobile phone tracking tracks the current position of a mobile phone even on the move. To locate the phone, it must emit at least the roaming signal to contact the next nearby antenna tower, but the process does not require an active call. GSM localisation is then done by multilateration based on the signal strength to nearby antenna masts.

Mobile positioning, i.e. location based service that discloses the actual coordinates of a mobile phone bearer, is a technology used by telecommunication companies to approximate where a mobile phone, and thereby also its user (bearer), temporarily resides. The more properly applied term locating refers to the purpose rather than a positioning process. Such service is offered as an option of the class of location-based services (LBS).

Technology
The technology of locating is based on measuring power levels and antenna patterns and uses the concept that a mobile phone always communicates wirelessly with one of the closest base stations, so if you know which base station the phone communicates with, you know that the phone is close to the respective base station.

Advanced systems determine the sector in which the mobile phone resides and roughly estimate also the distance to the base station. Further approximation can be done by interpolating signals between adjacent antenna towers. Qualified services may achieve a precision of down to 50 meters in urban areas where mobile traffic and density of antenna towers (base stations) is sufficiently high. Rural and desolate areas may see miles between base stations and therefore determine locations less precisely.

Operational purpose
In order to route calls to a phone the cell towers listen for a signal sent from the phone and negotiate which tower is best able to communicate with the phone. As the phone changes location, the antenna towers monitor the signal and the phone is roamed to an adjacent tower as appropriate.

By comparing the relative signal strength from multiple antenna towers a general location of a phone can be roughly determined. Other means is the antenna pattern that supports angular determination and phase dicrimination.

Newer phones may also allow the tracking of the phone even when turned on and not active in a telephone call-. This results from the roaming procedures that perform hand over of the phone from one base station to another

Bearer interest
A phone's location can be uploaded to a common web site where one's "friends and family" can view one's last reported position. Newer phones may have built-in GPS receivers which could be used in a similar fashion, but with much higher accuracy.

Privacy
Locating or positioning touches upon delicate privacy issues, since it enables someone to check where a person is without the person's consent. Strict ethics and security measures are strongly recommended for services that employ positioning, and the user must give an informed, explicit consent to a service provider before the service provider can compute positioning data from the user's mobile phone.

In Europe, where most countries have a constitutional guarantee on the secrecy of correspondence, location data obtained from mobile phone networks is usually given the same protection as the communication itself. The United States however has no explicit constitutional guarantee on the privacy of telecommunications, so use of location data is limited by law.

With tolling systems, as in Germany, the locating of vehicles is equally sensitive to the constitutional guarantee on the secrecy of correspondence and thus any further use of tolling information beyond deducting the road fee is prohibited. That leads to the strange situation that even obviously criminal intent may not be interfered by such yet available technical means.

Officially, the authorities (like the police) can obtain permission to position phones in emergency cases where people (including criminals) are missing.

The FBI appears to have begun using a novel form of electronic surveillance in criminal investigations: remotely activating a mobile phone's microphone and using it to eavesdrop on nearby conversations. This works with or without locating. The technique is called a "roving bug," and was approved by top U.S. Department of Justice. A judge ruled that police use of such tracking in the USA will require a warrant showing probable cause.

The Electronic Frontier Foundation is tracking some cases, including USA v. Pen Register, regarding government tracking of individuals such as pedophiles and political activists.

Free Services
It is possible in user agreements on the site offering "Free" service that one is, in fact, allowing the cellular telephone number being tracked to be added to telemarketers' lists.