Cell phone companies will do this to find the location of a phone that has been used to call 911. It appears that many agencies are using this process to determine the location of phones that have not called 911, such as the phone of a kidnap victim.

The provision of GPS location info for 911 callers is governed by the FCC's E911 rules. Where can I find these? I am trying to determine the requisites for a request under this framework.

Also, how do you obtain emergency GPS info (no time for a warrant) on a phone when the phone was not used to call 911?