If you need a cheap way of listening to what's happening in a remote location, for instance if you want to check on your baby while she's sleeping, there's no need to buy expensive surveillance equipment or a purpose-built baby alarm. You can turn your mobile phone into a listening device that you can call up when you want to hear what's happening in another room or location.
Connect your mobile phone to its charger and plug it into a power supply in the room you want to monitor. Make sure that the phone is receiving a strong signal.
Plug the hands-free kit into the handset and set the phone's profile to silent, making sure that he vibrate function is off.
Switch the phone to auto answer. Most phones have a function that will answer calls automatically when activated. For some makes and models, you may need to download an additional application. Check your phone's manual if you are unsure how to activate this function.
Conceal the phone and any wiring if you do not want your listening device to be discovered.
Go to a remote location and call the handset you have set up as a listening device. It will answer automatically and you will be able to hear what is happening where you have placed it.
If you're using an older phone without an auto answer function and you can't download one, call the listening device and answer it manually after you have set it up. Keep the two phones connected to hear what is happening in the room where your device has been left.
It is illegal to record conversations without the participants' consent in some states.