To make your life easier, dfndr security offers an option to save an unknown number from an incoming call that has lasted more than two minutes.
Once the call is finished, a pop-up message will appear asking if you’d like to save the number as a new contact. If you want to save the number, select “Confirm”.
Once confirmed, you will be brought to the phone app to create a new contact with the number already added into the field. Fill out the rest of the contact information and save it.
The new number is now saved to your contacts list.