France blocks mobiles in theatres

[Guest]

Archived from groups: alt.cellular.fido (More info?)

> http://news.com.com/France+fries+cell+phones/2100-1039_3-5406796.html?tag=nl

France has passed a law allowing theatres to block cell phone signals.

However, the gadgets that provide the service allow outgoing calls to
emergency numbers.

Does anyone know how this is accomplished ?

If you're going to jam certain frequencies to prevent mobiles from working,
how would it still allow access to France's equivalent to 911 ?

Or will the equipment essentially be a picocell that captures phones in the
building instead of allowing them to lock onto outside towers ?

 

[Guest]

Archived from groups: alt.cellular.fido (More info?)

On Sat, 16 Oct 2004 14:41:09 -0400, JF Mezei wrote:

>> http://news.com.com/France+fries+cell+phones/2100-1039_3-5406796.html?tag=nl
>
> France has passed a law allowing theatres to block cell phone signals.
>
> However, the gadgets that provide the service allow outgoing calls to
> emergency numbers.
>
> Does anyone know how this is accomplished ?
>
> If you're going to jam certain frequencies to prevent mobiles from
> working, how would it still allow access to France's equivalent to 911 ?
>
> Or will the equipment essentially be a picocell that captures phones in
> the building instead of allowing them to lock onto outside towers ?

A GSM phone behaves very differently when trying to establish an
"emergency" call. It sets certain flags in the frame that announces it as
"emergency".

My guess is the "blockers" are actually quite intelligent. They probably
only block GSM frames that aren't emergency (probably with a short burst
of RF). Just a guess, but that's how I would do it. TTYL