One of the most powerful surveillance tools today is the spy cell phone. A simple GSM phone becomes a monitoring tool when spy software is installed into it. This allows the phone to trace and call monitored from any where in the world. It does not require any active internet connection to use the system. Even if the phone is not in the on mode you can still listen in to the conversations happening around that place. The person who installs the software is the only person who controls the system. There are many Bluetooth spy software in the market that are scams.