Call the 112 only in real life-threatening emergencies like:
Serious medical problems (unconscious person, important injuries, chest pain, seizure, bleeding)
Any type of fire (house, car, business)
Life-threatening situations (crimes, fights, people with weapons, robbery in progress, etc)
Do not call the 112 :
To test your mobile phone - you may block a real life-threatening emergency call
To laugh at the operators or to just hang up - respect operators who work under stress to help save lives, do not block real emergency calls by blocking lines
For non life-threatening emergencies or non-emergencies like property damage accidents, break-in to vehicles, theft of property, vandalism - especially when the suspect is gone - cars blocking the street. Call directly the local police.
However - when in doubt, dial it out - 112. You could save someone's life!