You may wish not to receive calls from people who withhold their number. Anonymous caller reject can be activated or deactivated on your line by dialing a * or # code from your telephone handset.
This Feature is activated by dialing *89. Whilst anonymous caller reject is active, you will not be able to receive any call from a person who has withheld their number. This includes doctors, hospitals, dentists etc.
You can deactivate this feature by dialing #89