This wonderful feature helps you turn your device into a perfect bugging device. How does it work?
The disadvantages are all the calls (silent calls) will be shown in the billing and you must pay costs to make calls. You can try to use function "Ambient Voice Recording". It is a new function since the year 2013. It records all sound surrounding and you can listen lively (delay 3 to 4 seconds only) and special after a live listening, you can have an audio file (to use as proof for example).
To turn a device into a bugging device, first, you need to turn on Auto Answer feature and set an administrating number (a 'monitor number'. Monitor number is the device number you will use to make a silent call to target iDevice (iPhone, iPad - the device which installed the application) and the target device will automatically receive the call from this monitor number without the device user awareness and you can hear all the sound and know everything happens surrounding the target device. Only monitor number can make a silent call to the target device. There will be no record of this call in Call History of the target device so there is no trace left.
When you make calls from your device to the target device your call will be auto-answered and you will be able to listen to the device surroundings. Please note that this feature will work if the device is locked. If the device is in use (unlocked) your call will be rejected.
This feature worked well in the past but it was disabled since the year 2017 because it does not allow to use this feature in most countries/regions. Please contact us in case you need it with legal.