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Thread: A little 411 on wireless E911

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    A little 411 on wireless E911

    Calling 911 from a cellphone is different from calling 911 from a landline. This can translate to longer response times. Note: By landline, I mean a real landline, not VOIP, the use of which can cause a problem, if the service even supports E911.

    One of the differences is where the call is routed. In some areas of California, an operator (or is it a dispatcher?) at a highway patrol comunications center will pick up the call. He or she must decide whether to transfer the call to local authorities. They usually will, if the emergency you're reporting is not on a highway. If they do transfer the call, an operator or dispatcher at the municipal or county emrgency communications center will pick up the phone and ask you what they need to know about the emergency. This, as you can imagine, means you'll have to wait longer to get help.
    If you are in a place where the highway patrol does not handle calls coming from your municipality or county, or neighboring municipalities or counties, your call could be forwarded to a neighboring municipality or county's communications center. This is because wireless carriers typically connect 911 calls to a communications center that has jurisdiction over the area where the tower is located. There was a story in the news once. A Bethesda, Maryland family's house caught on fire. A neighbor called 911 on a cellphone. Unfortunately, the neighborhood is in an area where cell phones on that network are connected to either a tower in Bethesda or a tower in Washington, D.C, and the neighbor's phone was connected to the tower in D.C. So someone in D.C picked up the 911 call. The neighbor gave the person the address, and the person sent the D.C fire department to a D.C building with the same address.

    Another difference is in how dispatchers and operators find you if you can't speak, and how long it takes to do so. Landlines are tied to an address. If you call 911 from a landline and can't give the address, the dispatcher can send a query to a database to get your address. This all happens pretty quickly. Because cell phones are portable, however, it can take at least ten minutes to get your location, if the technology he has available allows him to. The FCC set up two phases to help dispatchers find the location of the caller. Let me explain:


    Phase 1: After you call, the dispatcher has information like your name and phone number. They then query a database, which gives them the address of the tower you are connected to and the cell sector your phone is in. Wireless carriers have 6 minutes to give the dispatcher this information.
    Phase 2: The dispatcher then tries to narrow the range of possible locations. To do this, the dispatcher will request the approximate location from the wireless carrier. (I don't know why the dispatcher waits until he gets a response to his initial query. Maybe it's because some phones still don't support phase 2.) The network will either use the device's built-in location services or the phone's distance to other cell towers to determine the location.
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    WiggleWiggle dclamp's Avatar
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    Re: A little 411 on wireless E911

    Im not sure where you get getting your information but it is slightly incorrect.

    As soon as a 911 call is answered, The callers information is instantaneously shown on the screen. If the dispatch center has mapping capabilities, then it will also show on the map instantaneously.

    Its called an ANI/ALI system. Automated Number Identification and Automated Location Identification System. For Landlines, your Address is associated with your phone number and provided by your phone carrier. For Wireless, depending on the age of your phone, will provide Coordinates and Accuracy. Newer phones have WP2 (Wireless Phase 2) which will show with 95% accuracy and is based off of GPS. If you have an older phone it will show with WP1, about 40-50% accuracy and is generally based off of triangulation. Not sure where you got that it takes 10 minutes to get callers locations. If the caller is unable to speak they send officers to the location where the phone pings.

    All wireless 911 calls made in California are directed to the PSAP with jurisdiction based off of the Coordinates. If the caller lands within a freeway, they are routed to CHP. Within a City, then the city police. Unincorporated areas, to the local sheriff.

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    Re: A little 411 on wireless E911

    Quote Originally Posted by dclamp
    For Wireless, depending on the age of your phone, will provide Coordinates and Accuracy. Newer phones have WP2 (Wireless Phase 2) which will show with 95% accuracy and is based off of GPS. If you have an older phone it will show with WP1, about 40-50% accuracy and is generally based off of triangulation. Not sure where you got that it takes 10 minutes to get callers locations. If the caller is unable to speak they send officers to the location where the phone pings.

    All wireless 911 calls made in California are directed to the PSAP with jurisdiction based off of the Coordinates. If the caller lands within a freeway, they are routed to CHP. Within a City, then the city police. Unincorporated areas, to the local sheriff.
    I think this information is slightly incorrect.

    1) The FCC hopes to have all networks transmitting GPS data from new phones in a few years. Certain networks like AT&T currently figure out where the phone is based on its distance to nearby cell towers.
    2) There are police departments and sheriff's offices in CA that can't afford to handlewireless 911 calls, so the highway patrol handles them.
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    Re: A little 411 on wireless E911

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    WiggleWiggle dclamp's Avatar
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    Re: A little 411 on wireless E911

    Quote Originally Posted by moonman239 View Post
    I think this information is slightly incorrect.

    1) The FCC hopes to have all networks transmitting GPS data from new phones in a few years. Certain networks like AT&T currently figure out where the phone is based on its distance to nearby cell towers.
    2) There are police departments and sheriff's offices in CA that can't afford to handlewireless 911 calls, so the highway patrol handles them.
    Its not. Considering I have formal training in 911 call taking and technology, I would know better than someone who does not.

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    Re: A little 411 on wireless E911

    Quote Originally Posted by dclamp View Post
    I would know better than someone who does not.
    I truly hope that nobody has any quibble with THAT statement.
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    WiggleWiggle dclamp's Avatar
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    Re: A little 411 on wireless E911

    Quote Originally Posted by Shaggy Hiker View Post
    I truly hope that nobody has any quibble with THAT statement.
    It is a catch all statement.

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    Re: A little 411 on wireless E911

    Quote Originally Posted by dclamp View Post
    Its not. Considering I have formal training in 911 call taking and technology, I would know better than someone who does not.
    Oh, no. I understand that clearly. I just don't really think you have all your facts straight.

    I invite you to have a look at this article. Highway patrol given outsized load of wireless 911 calls
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    Re: A little 411 on wireless E911

    Quote Originally Posted by dclamp View Post
    Its not. Considering I have formal training in 911 call taking and technology, I would know better than someone who does not.
    Ok, it turns out you were right, to some extent. What really happens when you call 911 is that a computer determines where to route your call based on the location of the cell mast and, in cases where a caller could be calling from the highway, the cell sector. (There are multiple.) If the computer determines that you're most likely on a highway, it will route your call to the nearest CHP communications center. If it determines that you're most likely in an unincorporated area of a county, it will route your call to that county's emergency dispatch center. If it determines that you're most likely in a municipality, it will route your call to that municipality's dispatch center. (Side note: As far as I know, all dispatch centers are run by the law enforcement agency that serves the area the center serves.) Again, that's only in cases where the appropriate dispatch center can receive 911 calls from cell phones. If they can't, another agency such as the county emergency dispatch center or the communications center of the CHP region that the area is in.
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