{{Short description|Identifying the location of a mobile phone}} thumb|An indoor location tracking map on a mobile phone '''Mobile phone tracking''' is a process for identifying the location of a mobile phone, whether stationary or moving. Localization may be effected by a number of technologies, such as the multilateration of radio signals between (several) cell towers of the network and the phone or by simply using GPS tracking. To locate a mobile phone using multilateration of mobile radio signals, the phone must emit at least the idle signal to contact nearby antenna towers and does not require an active call. The Global System for Mobile Communications (GSM) is based on the phone's signal strength to nearby antenna masts.<ref>{{cite news|url=https://news.bbc.co.uk/2/hi/technology/4738219.stm |title=Tracking a suspect by any mobile phone: Tracking SIM and handset | work=BBC News | date=2005-08-03 | access-date=2010-01-02}}</ref>
Mobile positioning may be used for location-based services that disclose the actual coordinates of a mobile phone. Telecommunication companies use this to approximate the location of a mobile phone, and thereby also its user.<ref name="swang2008">[http://to.swang.googlepages.com/ICC2008LBSforMobilessimplifiedR2.pdf "Location Based Services for Mobiles: Technologies and Standards“], Shu Wang, Jungwon Min and Byung K. Yi, [http://www.ieee-icc.org/ IEEE International Conference on Communication (ICC) 2008], Beijing, China</ref>
== Technology == The location of a mobile phone can be determined using several complementary technologies. Modern phones typically use a hybrid positioning system that combines these methods to provide the fastest and most accurate location possible.
=== Handset-based positioning === This is the most common method, where the device itself calculates its own position. * GNSS / GPS: The phone uses a built-in receiver to calculate its precise location from signals broadcast by satellite navigation constellations (like GPS, GLONASS, or Galileo). This is the most accurate method when outdoors. * Wi-Fi Positioning: In areas with poor satellite reception, such as indoors or in dense "urban canyons," the phone can scan for nearby Wi-Fi networks. It then calculates its position by cross-referencing the unique identifiers (BSSIDs) of these networks against a global, crowdsourced database of their locations.<ref>{{cite web|title=Q&A on Location Data|url=https://www.apple.com/pr/library/2011/04/27Apple-Q-A-on-Location-Data.html|work=apple.com|publisher=Apple|access-date=2013-03-08}}</ref> * '''Fingerprinting''': This technique records the "signature" of home and neighboring cell signal strengths at different points in an area. The device can then match its current signal signature to this database to determine its location.<ref>{{Cite journal|last1=Ibrahim|first1=M.|last2=Youssef|first2=M.|date=2012-01-01|title=CellSense: An Accurate Energy-Efficient GSM Positioning System|journal=IEEE Transactions on Vehicular Technology|volume=61|issue=1|pages=286–296|doi=10.1109/TVT.2011.2173771|issn=0018-9545|arxiv=1110.3425|s2cid=14790516 }}</ref>
=== Network-based positioning === This method relies on the cellular network infrastructure to determine the phone's location. The advantage is that it can be implemented non-intrusively by the service provider without any special software on the handset.<ref name=":0">[http://emits.sso.esa.int/emits-doc/1-5200-RD24-Mobile-positioning-using-wireless-networks.pdf Mobile Positioning Using Wireless Networks]</ref> * Cell ID: The least accurate method, which uses the known location of the single cell tower the phone is communicating with. Its precision is low, especially in rural areas where cell towers are far apart. * Multilateration: More advanced systems use the signal strength and timing from multiple adjacent cell towers to triangulate the phone's position. This is more accurate in urban areas where cell tower density is high.<ref>{{Cite book|last1=Laitinen|first1=H.|last2=Lahteenmaki|first2=J.|last3=Nordstrom|first3=T.|title=IEEE VTS 53rd Vehicular Technology Conference, Spring 2001. Proceedings (Cat. No.01CH37202) |chapter=Database correlation method for GSM location |date=2001|location=Rhodes, Greece|publisher=IEEE|volume=4|pages=2504–2508|doi=10.1109/VETECS.2001.944052|isbn=9780780367289|s2cid=195858053 }}</ref>
=== Data transmission in applications === For any location-based service to function, the position data calculated by the phone (whether from GPS, Wi-Fi, or the network) must be transmitted to a server. The phone's built-in cellular modem sends this telemetry data over the mobile network (e.g., 4G/5G).
This "phone-as-a-sensor" model is the foundation for many modern on-demand services and is a key part of fleet digitalization. Applications for food delivery, courier services, and ride-hailing (like Uber or Lyft) rely on the phone's transmitted location data to function. The phone itself acts as the GPS tracking unit for the service's fleet management platform, allowing it to dispatch the nearest driver, provide customers with a real-time track and trace map, and calculate billing. The reliability of these services depends on this constant data connection; for example, the shutdown of older 3G networks required many commercial services to ensure their devices were 4G or 5G capable to maintain connectivity.<ref>{{cite web |url=https://www.forbes.com/councils/forbestechcouncil/2023/08/03/will-the-3g-sunset-leave-supply-chains-in-the-dark/ |title=Will The 3G Sunset Leave Supply Chains In The Dark? |website=Forbes |date=August 3, 2023 |access-date=October 7, 2025}}</ref>
=== Interception === Law enforcement and intelligence agencies conduct cellphone surveillance by intercepting and collecting data, including location data, with devices and methods including IMSI-catchers, such as the Stingray phone tracker.<ref>{{Cite journal |last=Slobogin |first=Christopher |last2=Brayne |first2=Sarah |date=2023 |title=Surveillance Technologies and Constitutional Law |url=https://pmc.ncbi.nlm.nih.gov/articles/PMC10704392/ |journal=Annual Review of Criminology |volume=6 |pages=219–240 |doi=10.1146/annurev-criminol-030421-035102 |issn=2572-4568 |pmc=10704392 |pmid=38074421}}</ref>
== Operational purpose == In order to route calls to a phone, 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 make use of the antenna pattern, which supports angular determination and phase discrimination.
Newer phones may also allow the tracking of the phone even when turned on but 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.<ref>{{cite web |url=http://www.thechicagosyndicate.com/2006/12/roving-bug-in-cell-phones-used-by-fbi.html |work=The Chicago Syndicate -BLOG |title=Roving Bug in Cell Phones Used By FBI to Eavesdrop on Syndicate |author=Declan McCullagh and Anne Broache |date=6 December 2008 }}</ref>
== Consumer applications ==
A phone's location can be shared with friends and family, posted to a public website, recorded locally, or shared with other users of a smartphone app. The inclusion of GPS receivers on smartphones has made geographical apps nearly ubiquitous on these devices. Specific applications include: * Geo-fence specific locations of interest such as No Fly Zones * GPS navigation and maps * Locator apps like Find My Friends * Dating apps like Grindr * Recording a journey, for example to show a hiking accomplishment * For quantified self purposes such as fitness tracking * GPS drawing
In January 2019, the location of her iPhone as determined by her sister helped Boston police find kidnapping victim Olivia Ambrose.<ref>{{Cite web|url=https://www.bostonglobe.com/business/2019/01/23/how-common-smartphone-app-helped-find-missing-woman/RBkDlEaBIBkOIplzJPrtDK/story.html|title=A common smartphone feature helped find missing woman - The Boston Globe|website=BostonGlobe.com}}</ref>
== Privacy == Locating or positioning touches upon delicate privacy issues, since it enables someone to check where a person is without the person's consent.<ref>{{cite web |last1=Waxman |first1=Seth |title=Brief for technology companies as amici curiae in support of neither party |url=http://www.scotusblog.com/wp-content/uploads/2017/08/16-402-ac-technology-companies.pdf |website=scotusblog |publisher=Supreme Court of the United States |access-date=23 June 2018}}</ref> Strict ethics and security measures are strongly recommended for services that employ positioning.
In 2012 Malte Spitz held a TED talk<ref>{{cite web | url=https://www.ted.com/talks/malte_spitz_your_phone_company_is_watching | title=Your phone company is watching - TEDGlobal 2012 | work=ted.com | date=June 2012 | access-date=26 January 2016}}</ref> on the issue of mobile phone privacy in which he showcased his own stored data that he received from Deutsche Telekom after suing the company. He described the data, which consists of 35,830 lines of data collected during the span of Germany's data retention at the time, saying, "This is six months of my life [...] You can see where I am, when I sleep at night, what I'm doing." He partnered up with ZEIT Online and made his information publicly available in an [http://www.zeit.de/datenschutz/malte-spitz-vorratsdaten interactive map] which allows users to watch his entire movements during that time in fast-forward. Spitz concluded that technology consumers are the key to challenging privacy norms in today's society who "have to fight for self determination in the digital age."<ref>{{cite news | url=http://www.huffingtonpost.com/2012/07/25/malte-spitzs-ted-talk-_n_1701775.html | title=Malte Spitz's TED Talk Takes On Mobile Phone Privacy Debate (VIDEO) | newspaper=Huffington Post | date=25 July 2012 | access-date=26 January 2016 | author=Fitzgerald, Britney}}</ref><ref>{{cite news | url=http://www.zeit.de/digital/datenschutz/2011-03/data-protection-malte-spitz | title=Betrayed by our own data | publisher=ZEIT | date=10 March 2011 | access-date=26 January 2016 | author=Biermann, Kai| newspaper=Die Zeit }}</ref>
===China=== The Chinese government has proposed using this technology to track commuting patterns of Beijing city residents.<ref>{{cite news| url=http://voices.washingtonpost.com/posttech/2011/03/china_said_it_may_begin.html| archive-url=https://web.archive.org/web/20110624100746/http://voices.washingtonpost.com/posttech/2011/03/china_said_it_may_begin.html| url-status=dead| archive-date=June 24, 2011| author=Cecilia Kang| title=China plans to track cellphone users, sparking human rights concerns| newspaper=The Washington Post| date=March 3, 2011}}</ref> Aggregate presence of mobile phone users could be tracked in a privacy-preserving fashion.<ref>D. Quercia, Ilias Leontiadis, Liam McNamara, Cecilia Mascolo, Jon Crowcroft (2011). [http://www.cl.cam.ac.uk/~dq209/publications/spotme.pdf SpotME If You Can: Randomized Responses for Location Obfuscation on Mobile Phones. ] ''IEEE ICDCS''</ref> This location data was used to locate protesters during protests in Beijing in 2022.<ref>{{Cite web |last=Xiong |first=Nectar Gan, Yong |date=2022-12-02 |title=Chinese police are using cellphone data to track down protesters |url=https://www.cnn.com/2022/12/02/china/china-beijing-protests-police-mobile-signal-intl-hnk/index.html |access-date=2022-12-03 |website=CNN |language=en}}</ref>
===Europe=== In Europe most countries have a constitutional guarantee on the secrecy of correspondence, and location data obtained from mobile phone networks is usually given the same protection as the communication itself.<ref>{{Cite book|last=Spyropoulos, Philippos K.|title=Constitutional law in Greece|date=2009|publisher=Kluwer Law International|others=Fortsakis, Théodore.|isbn=978-90-411-2878-2|location=Netherlands|oclc=383848443}}</ref><ref>{{Citation|last=Campbell|first=John|title=The origins and development of the right to privacy|date=2020|url=http://dx.doi.org/10.4337/9781788970594.00008|work=Comparative Privacy and Defamation|pages=9–23|publisher=Edward Elgar Publishing|doi=10.4337/9781788970594.00008 |isbn=978-1-78897-059-4|s2cid=225586361 |access-date=2020-10-24|url-access=subscription}}</ref><ref>"Chapter X, Fundamental Rights and Duties of Citizens, Article 128". [http://www.departments.bucknell.edu/russian/const/36cons04.html#chap10 ''1936 Constitution of the USSR''.] <q>The inviolability of the homes of citizens and privacy of correspondence are protected by law.</q></ref><ref>Roxana Maria Roba. [https://old.upm.ro/facultati_departamente/ea/RePEc/curentul_juridic/rcj09/recjurid091_10F.pdf The Legal Protection of the Secrecy of Correspondence], ''Curentul "Juridic"'' ([https://web.archive.org/web/20150518070822/http://revcurentjur.ro/arhiva/attachments_200901/recjurid091_10F.pdf archived]), 2009, number 1, Tîrgu-Mureş, Romania.</ref>
===United States=== In the United States, there is a limited constitutional guarantee on the privacy of telecommunications through the Fourth Amendment.<ref name="Carpenter">{{cite court |litigants=Carpenter v. United States |vol=583 |reporter=U.S. |court=Supreme Court of the United States |date=22 June 2018 |url=https://www.law.cornell.edu/supremecourt/text/16-402 |access-date=June 22, 2018 |quote=The Government's acquisition of Carpenter's cell-site records was a Fourth Amendment search.}}</ref><ref name="Riley">{{cite court |litigants=Riley v. California |vol=573 |reporter=U.S. |court=Supreme Court of the United States |date=25 June 2014 |url=https://www.law.cornell.edu/supremecourt/text/13-132 |access-date=June 23, 2018 |quote=Required a warrant to search mobile telecommunications devices.}}</ref><ref name="Jones">{{cite court |litigants=United States v. Jones |vol=565 |reporter=U.S. |opinion=400 |court=Supreme Court of the United States |date=23 January 2012 |url=https://www.law.cornell.edu/supremecourt/text/10-1259 |access-date=June 23, 2018 |quote=Limited use of GPS devices [such as in a cell phone] to track movements.}}</ref><ref name="Katz">{{cite court |litigants=Katz v. United States |vol=389 |reporter=U.S. |opinion=347 |court=Supreme Court of the United States |date=18 December 18, 1967 |url=https://www.law.cornell.edu/supremecourt/text/389/347 |access-date=June 23, 2018 |quote=(a) that an enclosed telephone booth is an area where, like a home, and unlike a field, a person has '''a constitutionally protected reasonable expectation of privacy;''' (b) that '''electronic''' as well as physical '''intrusion into a place that is in this sense private may constitute a violation of the Fourth Amendment;''' and (c) that an invasion of a constitutionally protected area by federal authorities is, as the Court has long held, presumptively unreasonable in the absence of a search warrant.}}</ref><ref name="Jackson">{{cite court |litigants=Ex parte Jackson |vol=96 |reporter=U.S. |opinion=727 |court=Supreme Court of the United States |date=1878 |url=https://supreme.justia.com/cases/federal/us/96/727/case.html |access-date=June 23, 2018 |quote=Letters and sealed packages subject to letter postage in the mail can be opened and examined only under like warrant, issued upon similar oath or affirmation, particularly describing the thing to be seized, as is required when papers are subjected to search in one's own household. The constitutional guaranty of the right of the people to be secure in their papers against unreasonable searches and seizures extends to their papers, thus closed against inspection, wherever they may be.}}</ref> The use of location data is further limited by statutory,<ref name="SCA">{{cite web |title=Stored Communications Act (18 U.S. Code § 2703(d) - Required disclosure of customer communications or records)|url=https://www.law.cornell.edu/uscode/text/18/2703 |quote=Requirements for Court Order.— A court order for disclosure under subsection (b) or (c) may be issued by any court that is a court of competent jurisdiction and '''shall issue only if the governmental entity offers specific and articulable facts showing that there are reasonable grounds to believe that the contents of a wire or electronic communication, or the records or other information sought, are relevant and material to an ongoing criminal investigation. In the case of a State governmental authority, such a court order shall not issue if prohibited by the law of such State.''' A court issuing an order pursuant to this section, on a motion made promptly by the service provider, may quash or modify such order, if the information or records requested are unusually voluminous in nature or compliance with such order otherwise would cause an undue burden on such provider.}}</ref> administrative,<ref>{{Cite web|url=https://www.law.cornell.edu/cfr/text/47/part-0/subpart-E|title=47 CFR Subpart E - Privacy Act Regulations|website=LII / Legal Information Institute}}</ref> and case law.<ref name="Carpenter"/><ref name="Karo">{{cite court |litigants=United States v. Karo |vol=468 |reporter=U.S. |opinion=705 |court=Supreme Court of the United States |date=3 July 1984 |url=https://www.law.cornell.edu/supremecourt/text/468/705 |access-date=June 22, 2018 |quote=the use of a beeper to conduct surveillance on Karo and his accomplices constituted an unlawful search and seizure in violation of the Fourth Amendment.}}</ref> Police access of seven days of a citizen's location data is unquestionably enough to be a fourth amendment search requiring both probable cause and a warrant.<ref name="Carpenter"/><ref>{{cite news |last1=Liptak |first1=Adam |author-link1=Adam Liptak |date=23 June 2018 |title=Warrant Required for Cellphone Tracking Data |url=https://www.nytimes.com/2018/06/22/us/politics/supreme-court-warrants-cell-phone-privacy.html |format=print |language=en |volume=CLXII |issue=58,002 |edition=National |work=The New York Times |pages=A1, A16 |access-date=23 June 2018 |quote=“We decline to grant the state unrestricted access to a wireless carrier's database of physical location information,” Chief Justice John G. Roberts Jr. wrote for the majority. ... “Mapping a cellphone's location over the course of 127 days provides an all-encompassing record of the holder's whereabouts,” he wrote, going on to quote from an earlier opinion. “As with GPS information, the time-stamped data provides an intimate window into a person's life, revealing not only his particular movements, but through them his ‘familial, political, professional, religious and sexual associations.'” ... “cellphones and the services they provide are ‘such a pervasive and insistent part of daily life' that carrying one is indispensable to participation in modern society.”}}</ref>
In June 2018, the United States Supreme Court ruled in ''Carpenter v. United States'' that the government violates the Fourth Amendment by accessing historical records containing the physical locations of cellphones without a search warrant.<ref>{{Cite journal|last=Keyaerts|first=K.|date=2018|title=United States ∙ Carpenter v US: Supreme Court Rules Police Need a Warrant to Obtain Cell-Site Location Information|url=http://dx.doi.org/10.21552/edpl/2018/4/17|journal=European Data Protection Law Review|volume=4|issue=4|pages=525–530|doi=10.21552/edpl/2018/4/17|issn=2364-2831|url-access=subscription}}</ref>
== See also == {{div col|colwidth=30em}}
* ''Carpenter v. United States'' * Cellphone surveillance * Geofence warrant * Geolocation * GLONASS Russian "Global Navigation Satellite System" * Google Latitude * GPS phone * Indoor positioning * Information privacy * IMEI number * Local positioning system * Mass surveillance * Mobile dating * Mobile device forensics * Mobile identification number * Mobile security * Positioning technology * Phone surveillance * Radio resource location services protocol * Real-time locating system * ''Riley v. California'' * Satellite navigation * Secure telephone * Triggerfish (surveillance) * ''United States v. Jones (2012)'' * ''United States v. Karo'' * Vehicle tracking system {{div col end}}
== References == {{Reflist}}
==External links== * {{cite journal|url=https://www.cs.umd.edu/~jonf/publications/Varshavsky_AreGSMPhonesTheSolutionForLocalization_WMCSA2006.pdf|title=Are GSM phones THE solution for localization?|journal=In 7th IEEE Workshop on Mobile Computing Systems and Applications (HotMobile)|publisher=IEEE Computer Society|pages=20–28|first1=Alex|last1=Varshavsky|first2=Mikey|last2=Chen|first3=Jon|last3=Froehlich|first4=Dirk|last4=Haehnel|first5=Jeffrey|last5=Hightower|first6=Anthony|last6=Lamarca|first7=Fred|last7=Potter|first8=Timothy|last8=Sohn|first9=Karen|last9=Tang|first10=Ian|last10=Smith}} * {{cite journal|url=https://arstechnica.com/business/2012/02/location-tracking-of-gsm-cellphones-now-easier-and-cheaper-than-ever/|title= Location tracking of GSM cellphones: now easier (and cheaper) than ever|author=Dan Goodin|date=17 February 2012|journal=Arstechnica|publisher=Conde Nast}}
{{Mobile phones}} {{Positional tracking}}
{{DEFAULTSORT:Mobile Phone Tracking}} Category:GSM standard Category:Mobile technology Category:Crime prevention Category:Criminal investigation Category:Espionage techniques Category:Mobile telecommunication services Category:Privacy Category:Geopositioning Category:Tracking