In a random assessment of the use of “silent SMS” (also called “stealth ping”) by Berlin prosecution authorities, the Berlin Data Protection Commissioner has detected severe shortcomings in relation to aspects of its privacy. Silent SMS are messages that do not appear on the display of the mobile phone and trigger no acoustic signal. They can be used to locate a person and to create a precise movement profile.
According to the assessment, the sending of silent SMS was often not recorded properly or did not seem to be necessary. In most cases, the persons concerned had not been informed. The Commissioner thus called for a clearly defined legal basis for silent SMS in investigative procedures and a thorough control of this practice.
Article on Questionable Use of Silent SMS (PDF) (in German)