Here in Italy we still don’t have an unique number for emergencies. It is sad, because you can get confused by too many different numbers like 112 (Carabinieri), 113 (Police), 115 (Firefighters), 117 (Financial Police), 118 (Medical emergency), 1515 (State Forestry Department), 1530 (Cost guard). However if you call Carabinieri they should forward your call to the right service.
In many country around the world (but not US) and in almost all country in the EU, 112 is the number for every kind of emergency. Mobile phones let call it even if the keyboard is locked or there isn’t a SIM installed and when you dial it GSM system will redirect you to the right emergency number for your country if it isn’t the 112 (ex. 000 for Australia). Finally, did you know that 11th February (11/2) is the 112 day in Europe?
Learn all information about 112 emergency number on Wikipedia.