Probably the biggest cause of 911 misdials is the proverbial "butt dial" where users accidentally hit the speed dial sequence for 911 on their mobile phone while in their pocket. Enterprise PBXs are also a common source of calls to 911 when the user didn't intentionally plan on making that call. The problem here is that in many cases the PBX doesn't report station level caller ID, or if it does, in many cases the carrier will overwrite that information with the main billing telephone number.