In the USA its 311

https://www.fcc.gov/consumers/guides/nationally-assigned-3-d...

It’s just a regular phone number, so it depends what department you are trying to call. Google or a phone book is what you need.

You might have to google it because it's not standardized across the country

https://www.google.com/search?q=police+non+emergency+number+...

The one thing you can do is call 911 and when they respond, just say "I need the non-emergency line" and they'll usually transfer you immediately or just check quickly with you. Just don't waffle on.