Many phones will let you disconnect from 911, most cell phones will go into emergency mode for around 5 minutes after the call and will block all calls except the 911 center unless you cancel it. If you listen to a scanner you will hear a few run for a 911 hangup. Ive hung up on one city before here in michigan, by mistake, and they did nothing, but if you do that to a county or suburb 911 center most of the time they will call back after they have triangulated your cell position( if using a landline all the info pops right up) and have dispatched two units or a doubled up unit.