On Wed, 13 Apr 2016, Jay Hennigan wrote:
On 4/13/16 4:28 PM, Larry Sheldon wrote:
I am in frequent contact by a person that has a 917 NNX-XXXX-numbered telephone who spends a lot of time with a person that has a 408 NNX-XXXX-numbered telephone, and they both live in Metropolitan Boston
When either of those people dial 9-1-1, where does the ambulance show up?
I suspect your response was sarcastic, but when you dig into what really happens, it's not nearly as sophisticated as one might hope. If the numbers are land or VoIP lines, and the address associated with the numbers are registered with the Automatic Location Information (ALI) database run by ILECs or 3rd parties to fetch the address keyed on the calling number, and the 911 PSAP is E911 capable, they operator will see the ALI address. If they are mobile devices, it depends. Basic gives you nothing (all phones since 2003 should have GPS, but people hang on to phones a long time..); Phase I Enhanced gives you the location of the cell site/tower, Phase II gives you lat/lon within 50 to 300 meters within 6 minutes of a request by the PSAP. Yep, the PSAP has to make a request for the phone location to the carrier, in which they have 6 minutes to reply. I assume this is or can be automated. After 6 minutes, you could be a long way away from where you started the call. If the phone numbers are not in the ALI, or are not wireless, or the PSAP (Public Safety Answering Point, the 911 office) is not set up for e911, they probably get nothing, relying solely on the caller to provide location information. Beckman --------------------------------------------------------------------------- Peter Beckman Internet Guy beckman@angryox.com http://www.angryox.com/ ---------------------------------------------------------------------------