Matthias Monroy

With silent SMS, cell site analysis and IMSI catchers, authorities can pinpoint the location of a mobile device to within a few metres.

Last year, the German Federal Criminal Police sent about 68,000 silent SMS in 33 cases (one of which was a danger aversion case), which is a significant increase compared to preceding years. The Federal Police sent around 48,000 silent text messages in 56 criminal proceedings, which is roughly the average of past years. This is stated in the answer to a parliamentary question by the Left Party in the Bundestag.

With a silent SMS, a communication process is triggered, which can then be queried via the telecommunications providers. Thereby, the mobile phone cells in which the users were located are provided to the authorities. Location in conurbations is thus possible to an accuracy of a few metres, but with the help of Google’s geolocation, it is apparently much more precise.

Until 2012, the Federal Government had also openly communicated figures on silent text messages by the Customs Criminal Investigation Offices, which are even higher than those used by the BKA or the Federal Police. Since 2018, the Ministry of the Interior has been even more secretive about the Federal Office for the Protection of the Constitution, and this information can now only be viewed at the Bundestag’s Secret Office. The reason given is that the individual pieces of information from the annual enquiries could „condense into a comprehensive situational picture“. Information on silent SMS from the Federal Intelligence Service, however, remains completely secret.

IMSI catchers often from the federal states

While the telephone number of the person concerned must be known in order to send a silent SMS, an IMSI catcher can also be used to search for nearby unknown telephones or persons. The equipment tricks the phone into thinking it is in a mobile phone cell, into which it automatically logs on. This makes the phone and its device number known to the authorities. These can then be used for further investigations.

According to the answer, the BKA has used the method in five „already completed danger aversion procedures or investigations“, the Federal Police in a further 44 cases. Another 17 operations were carried out by state authorities under the auspices of the Office of the Attorney General.

There are no figures for customs, but it is reported that the financial authorities use the technology of the BKA, the Federal Police and many federal states for their operations.

Cell site analysis mainly by state authorities

A cell site analysis can also be used to identify unknown telephones or persons, but this measure – as far as is known – is, like geolocation with the help of Google Maps, in Germany mainly used retrospectively. For this purpose, mobile phone cells in which for example a crime occurred, are mapped and for a certain period of time all phone and device numbers registered there are queried from the providers. Afterwards, their owners can be identified.

In 2021, the BKA carried out cell site analysis in four completed cases, one of which was commissioned by the Office of the Attorney General. The Federal Police used it in 45 cases. The federal secret services are not allowed to use the measure in the first place, which is why it had not been used.

The fact that the BKA and the Federal Police rarely use cell site analysis is actually not surprising, as the measure is mainly used by state authorities. For example, the Berlin police had ordered over 600 of it in 2019, and this number is growing steadily. A similar picture can be seen with silent SMS, the number of which was well over 300,000 in Berlin alone in the same year, and even almost 450,000 in 2018.

According to governmental reply, the Federal Police have also geolocated mobile phones in 15 cases after their owners reported them stolen. With regard to the Federal Criminal Police Office, the ministry remains cryptic. The authority had „not requested the data in question in any completed investigations“.

Correction: In a former version the article stated that the German Federal Police used so-called geo warrants, using the „Sensorvault“ by Google Maps. But this wrong. Three years ago, the New York Times drew attention to the increasing use of such geolocation by police forces and secret services. The technology processes location information which remains recorded on Android devices, iPhones and iPads for several years. According to the newspaper, hundreds of millions of devices are recorded in it and its information goes back „nearly a decade“.

Image: Mael BALLAND on Unsplash.