GPS emergency call standards

Harald Welte laforge at
Thu Mar 12 22:12:27 CET 2009

On Tue, Feb 24, 2009 at 12:06:20PM +0100, Tilman Baumann wrote:
> Hi,
> I'm just wondering if there are any open standards for emergency  
> services for location.
> I'm thinking about services like  
> (European, websites in other languages should be available)
>   A SMS to the respective emergency (112, 911) number containing the  
> GPS position could be a start, but then someone has to read it.
> I would guess there is a standard for a computer readable format.
> Building a emergency call app would be a nice thing to have.
> PS: According to Wikipedia, 112 works on all GSM networks no matter if  
> the number is a emergency number in tie state.

that depends on what the network operator does.  The SIM card has a list of
emergency numbers.  If you call one of those numbers, or make an emergency
call without a SIM card inserted, the phone will do itts request for a physical
channel indicating its a EMERGENCY call, and then use EMERGENCY SETUP instead
of SETUP, so the network can decide to rather kill somebody elses call and free
resources for your emergency call in case the cell is otherwise full.

that's at least the theory from the protocol side.

the practical implementation can look quite different.  The German government
e.g. now legally mandates that an operator will refuse to take emergency
calls from phones with no SIM card inserted.

- Harald Welte <laforge at>         
Software for the world's first truly open Free Software mobile phone

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