911: Dial 911 for any emergencies. You will typically have a police official at your doorstep in a few minutes.
411: This is automated directory assistance. Dial 411 for the phone number of a person or a business establishment. You have to provide information like the city in which the person or Business is located, what kind of listing (this is "people" if you are looking for people or the type of Business like "Restaurants", if you are looking for Business listings). Then you give the name. Most of the times an operator comes on the line and you can get the required information.
(Area code)- 555-1212: This is the directory assistance for a different area code than the location that you are dialing from.
Toll free numbers: If you call a toll free number you do not have to pay anything. The called person (it is usually a company) will pay for your call. These numbers always start with 1-800, 1-888, 1877, 1-866, etc. Note that all calls to 1-900 numbers will be charged a per minute service fee.
