just wondering how to call the police or ambulance in case of an emergency in rome.
112 has now been standardised in all EU countries and many other European countries, sometimes in addition to those countries' traditional emergency numbers (eg the famous 999 in the UK and 110 in Germany).
Engrave that number in your memory. It is valid in all European countries for all emergency services (police, ambulance, fire etc.), in addition to the country-specific numbers. Calls are free, and you can call that number from a mobile phone even if there is no SIM card in the phone (it is a legal requirement to be able to do so).
I don't know if in all Europe but in European Union 112 is what here is 911. Besides they have their own country numbers which are different for police, different for firemen and also different for ambulance. If you have those numbers on hand, OK, just in case. But memorize 112 like we memorize 911 in this country and Canada.
You asked about ambulance and police. Why did you post the question in the Tourist Scams area of the Forums?