What does CALL 911 mean?
In most of North America, 911 is the number to phone for emergency services.
To call 911 means the same thing as to phone 911.
When you call 911, you talk to a trained person who asks you what the problem is. He or she will also ask you what your address is. As soon as 911 receives your call, they send the police, an ambulance and a firetruck.
If you phone from a landline (not a cell phone), they can trace your call, so you can receive emergency help even if you cannot speak.
See example: John’s wife fell down the stairs and was in terrible pain, so he called 911.