For discreet eavesdropping, covert listening devices are an excellent choice. They are also known as bugs or a wire, and consist of a miniature radio transmitter and a microphone. Recent technological developments have also included GSM SIM card applications as well, for listening devices that can be monitored by cellular phone from around the world at very little cost. Many listening devices are used in police investigations, but also for private investigations, most commonly for cases of infidelity. Transmissions of a mobile or wireless device can also be monitored, and it is also possible to capture the data from a wireless computer network. The bugs come with different shapes and sizes and forms. They can be built into ordinary, âin plain sightâ items, such as tissue boxes, calculators, or wall outlets. Some listening devices are of the appearance of a small shirt button, making the wearer of the shirt a mobile broadcasting point for the eavesdropping. Vehicle tracking systems are another commonly used system, as it is possible to listen to an in car discussion by the listening devices attached to the car tracking systems. These devices are prohibited to use, as it has been appealed in the courts as an invasion of privacy, and now a warrant must be obtained by law enforcement for this type of activity. Mobile phones are another target of eavesdropping, as the technology has reached a level where mobile phone microphones can be activated without physical acess to the handset, thus the cellular phone itself becomes the listening device. This type of eavesdropping is mostly used by law enforcement agencies and intelligence agencies, to eavesdrop without the knowledge of the target. The software is manipulated or over written so that the calls that are placed via the subroutine are not shown. A special feature is to accept the incoming call without showing on the mobile screen, but this feature is only possible when the mobile is not already engaged in communication. Listening devices continue to evolve, and it is important to understand that they can not always be detected. Conversations better left undisclosed should be carried out with the utmost discretion, because as the old saying goes, âyou never know who is listeningâ.