These three beeps are called the MNP Beep, a feature designed to know if the number you’re trying to reach has changed networks. To deactivate it: 1. Call 1966 2. Press 4 to change your MNP Beep settings 3. Press 1 to deactivate your MNP Beep.
If something is not that clear or you need some more information, please do not hesitate to contact us.