There are many types of listening devices including hardwired, Audio acoustic, Radio Frequency and optical bugs. In this article we will see some of the most frequently used listening device in the corporate world such as in Sydney PI private investigators.

GSM Bugs 

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The prolific listening device, GSM bugs operate in the same way as a mobile phone and perpetrator can in effect, dial in and silently listen to a conversation from anywhere around the world. A GSM bug is a small black box that can be discreetly hidden in a room or can be a purpose-built device such as mains adaptor, a power strip adaptor or a Phone charger or a PC Mouse. These are everyday objects that one expects to find in an office, but which could harbour a dangerous secret. High quality GSM bugs are available to buy online and from some high street shops.

 Miniature Voice Recorders 

Readily available on online stores, miniature recording devices like Edic – mini recording devices and those disguised as USB drives or credit cards are discrete audio recording devices made to be easily hidden or pass undetected by the unwary targets. Their use is limited by the battery life and storage, but in a large number of situations they can be just the weapon an infiltrator requires while being affordable and delivering high quality audio.

Mobile Phones As Bugs 

Mobile phones can also be used as working devices. They are programmed not to vibrate, ring or show any signs that they are being called. They auto answer and the caller can listen into conversation within the room. This type of attack can be done on a target phone which the perpetrator would then leave somewhere in the vicinity of the conversation they are targeting or could be done by sending someone an email or text with an attachment which once opened, would download the necessary software onto the target phone. The phone then can be controlled by the hacker who can remotely switch it on and listen from any other mobile phone anywhere around the world.

Phone Taps And Phone Bugs 

Two terms often interchange but in fact refer to two separate types of attacks are bug and tap.

Tap or Wiretap 

It is the device placed on the telephone system and is designed to intercept telephone conversations that are if no call is there then the tab is inactive.

Radio Frequency (RF) Transmitters 

Radio frequency RF bug includes the placing of radio transmitters in a room and listening with range using a receiver. The most famous example of use of an RF bug is the “Great Seal Bug” story when in 1952 RF listening devices were found in a carved wooden seal that had been presented to the US Embassy in Moscow and had hung there since 1946.


RF bugs can be small and can be concealed in just about anything including skirting boards, picture frames, etc. Relatively inexpensive and easy to use, you require a receiver to listen to them. Radio frequencies are given off by all spying devices nearly and these can be detected with specialized equipment as used by the engineers.


A bug is used to listen to room conversation but may use the telephone online as a facilitator. This means that all conversation in the area is susceptible to being overheard by the attacker and not just telephone calls.

Optical Devices 

They convert audio signals into transmitted light pulses which are then converted back to audio signals by a receiver.

The above-given listening devices can be helpful for private investigators and investigating agencies in carrying out their work successfully. There are many private investigators AU available for your needs.