Radio signals when off?

Discussion in 'iPhone' started by NewishMacGuy, May 29, 2008.

  1. NewishMacGuy macrumors 6502a


    Aug 2, 2007
    Why does my iPhone send signals to the tower when it's off (and in airplane mode)? I can tell because I can hear the interference over my computer speakers. Anyone know?
  2. skubish macrumors 68030


    Feb 2, 2005
    Ann Arbor, Michigan
    If it is truly off and not in standby it should not generate interference.

    All electronics can generate interference when powered on.
  3. retroneo macrumors 6502a

    Apr 22, 2005
    Unless you use the red slider, the phone isn't off...

    One nice thing about 3G is that it doesn't give that annoying 217Hz buzz on nearby speakers that GSM phones used to.
  4. ruinfx macrumors 6502a

    Feb 20, 2008
  5. fedup flyer macrumors regular

    Jan 18, 2008
    Even with the switch in the off position, the phone is not truly off. The E-911 chip is still active and can on be turned off by removing the battery
  6. avaloncourt macrumors 65816

    Oct 18, 2007
    You're a little confused about E911. If the iPhone had a GPS receiver then, yes, it very well could still be active in Airplane Mode but even A-GPS phones aren't going to transmit anything in Airplane Mode. That would make the mode useless. For the iPhone, E911 (that's the emergency service's equipment not the phone) uses tower-based location to find the phone through its GSM connection to the tower. If you're in Airplane Mode, all transmitting has been stopped thus preventing towers from locating the phone. That's the reason for Airplane Mode in the first place, so you're not transmitting anything on a plane.

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