When it comes to long distance surveillance, one of the main factors is keeping the operation as secret as it gets, and when you have to use a remote monitoring system, you should try to make them as invisible as possible.
Thanks to the ever increasing miniaturization of technology, particularly the kind that is used in this specific field, it is now possible to conceal listening devices inside objects of everyday use and of small size, such as table calculators, office lamps, inside what looks like a USB drive or, for example, on the inside of a computer mouse, which can be equipped with a GSM bug.
The GSM mouse, at a first glance, is a perfectly normal mouse which, along with carrying out its ordinary duties, on the inside conceals a small but important secret: a micro transmitter teamed up with a SIM card.
All you have to do is replace your old mouse with this new one, and as soon as it is connected to the USB port, the transmitter will immediately be available to start working, allowing a third party listener to hear in real time the conversations in the room, no matter where he is. To listen in, all you have to do is a phone call.
When it is not used as a remote listening device, your GSM mouse works normally, in order to avoid arising any possible suspicion in its unaware user. When you want to be in touch with him, all you have to do is call the number connected to the SIM card, and in a completely invisible fashion you will be able to listen in real time to environmental conversations taking place within a few meters around your spy mouse.
Once the surveillance operation is completed, just hang up and the mouse will keep working normally, while the bug is in standby mode.