"677" did not work for me (sprint). The other day I was following this car weaving in and out of its lane. After about three miles it was obvious the driver was having trouble keeping the car straight. Not wanting to overload the 911 system, I first tried 677 - "the number you have reached ...." was the answer I got. Next I tried "911" but all operators were busy so I hung up and kept a safe distance behind the impaired driver