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  1.    #1  
    I used to work for a company that did positioning with GSM phones and at the time there wasn't any handsets out there with the 650 abilities. I just tested S25phone with the Treo 650 GSM and it seems to get the cellid just fine. That means that any application can get this information by just a simple at-command.

    Cellid är the ID of the current radio tower (or basestation array) that the phone currently is talking to. There is not really much use to us unless we can translate the cellid to a real position in the real world. We used to make this by getting the celldatabase from the operator, not really something that they will release to anyone.

    But there is another solution. If you know your position (you're at home) you could walk around a bit and try to pick up which towers you get and then tell the application that if you are close to any of these towers, you are at home.

    The use here is unlimited. Set call forwarding and ringtones settings to different values for when you are at home or when you are out of the house.

    Another posibility is to use Bluetooth and see if you're close a specific computer (Your pc with a usb bluetooth device). If you have been close for at least 5 min then try to hotsync. And then hotsync every 2 hours. This could also change the call forwarding and ringtone settings.

    I'm not doing any palm development at this point so this is just throwing some ideas out there. If this is done already, then let me know.
    Last edited by swedenliketreo; 03/12/2005 at 04:38 AM.
    Unlocked GSM 680
  2. #2  
    What you're describing is called "location-based services"(LBS) and this has been a popular idea for over ten years. All of the ideas you've described have been done, some successfully, and many unsucessfully. Salling Clicker is an example of short-range LBS that has been sucessful. GSM cellid is only published by a few global GSM carriers (for example, currently none of the U.S. GSM carriers will release this info) so using that for LBS is poor. In addition, GSM triangulation is very difficult b/c most carriers use different tower equipment with different power outputs and in environments with different EM absorbtion spectra. It can be done, but it ends up giving you no more than an accuracy of several kilometers.

    U.S. CDMA carriers are getting behind LBS more, and SprintPCS recently published some APIs that some on this forum are working with. These APIs rely on the fact that CDMA phones often support the level of e-911 compliance that includes a GPS receiver. The phones can hear the GPS signal, but can calculate a position. In the event of a 911 call, the phone transmits all the GPS signals it can hear to the service provider. The provider then does the calculation to determine the phone's position. Sprint's API gives the developer access to results of the provider's position calculation.

    If you're interested in LBS and developing applications, you may instead want to consider switching from the Treo to the new iPaq when it is released. The new iPaq will have GSM/GPRS/EDGE and true GPS. I believe that this will be a good platform for prototyping a lot of interesting LBS applications.

    Could be fun!


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