FWIW, the view from the 9-1-1 call center may not be much different under the proposed legislation if the caller is unable to state the location where emergency help is required.
9-1-1 systems use Automatic Number Identification (ANI) and Automatic Location Information (ALI) to help call takers determine where a call is originating. Calls from PBX systems typically provide ANI information for the “main switchboard” number. This results in an ALI location of where that main switchboard is located without regard to the physical location of the extension that dialed 9-1-1.
To put that into more layman’s terms… A 9-1-1 call placed from room 2114 at a major Las Vegas Hotel may provide only the phone number of the front desk and address of the hotel - but not the room number. Emergency responders may have to conduct a room-by-room search to locate an incident.
And as md2000 mentioned, a PBX may be set up to provide phone service to multiple offices which are not at the same physical location. The 9-1-1 center may get location for the PBX switchboard but the emergency call may have originated from the other office across town.
Take home lesson - dialing 9-1-1 is only part of the battle. If at all possible the caller needs to clearly provide location information to assist responders in finding the location. That could be an address (1811 Main St, Little Town), landmark (Room 2114 at the Las Vegas Bellagio Hotel), or other location information (at sea at GPS coordinates 19’ 22" North, 83’ 41" West).