How to detect a turned off mobile?

[steve_rb]

can i check to see if a mobile is turned off

I have heard when a mobile is even turned off it broadcast signals which is detectable . This is why centeral network operator says for example "mobile is turned off" or " no responce to paging". Difference between these two messages indicates that some how network operator knows mobile is off or there is no responce to paging. This means when mobile is off it sends signals which tells operator it is in off status. I thought to use this signal for detecting a turned off hiden mobile in the vicinity of about few meters (let say two to five meters). I need matterials to read about this and make an electronic circuit to be able to detect this off state signal. Please post if you have info about this or please welcome if you would like to comment .

Regards

 

[ivar4ever]

turned off mobile still transmits

very good idea!!

**broken link removed**
this link is of a cellular phone detector. and they say that:

"Please note that the cell phone detectors will not pick up phones that are switched off or on standby (unless they are sending out an auto registration signal)."

but your argument has base too!!

 

[gied]

vlr purge

Some networks require mobile phone to report to the network when they are switched off. There are cases when mobile phone is not capable to send such message (say it was dropped on the ground and the battery flew off) or mobile entered area of no coverage.

So, if mobile has reported that it was turned off, network can tell caller, that mobile off. If network does not know about mobile switched off, then message about bad paging could be played.

However mobile does not send anything, when it is off.

 

[cabone]

auto registration signal

dear gied;

there is a feature which is called implicity detach which force the mobile to inform the system that it's going to turn off but this is only in of natural turn off so the system knows that the mbile will be out of duty and so it will not send it anymore signalling messages and so the system will simply inform any mobile tries to reach that specific user that the mobile is turned off, but in case off sudden turning off of the mobile when someone tries to reach that mobile it will send paging messages several times depending on some parameters and if the mobile didnot respond to it, it will declear that this mobile is out of coverage.

that is all

i hope that was usefull for you.

 

[Aasem_sadek]

auto registration signal

Dears Geid/Cabone,

both of u are talking about the same thing.

what i know abt this issue is the MS sends message to dettach itself from the system "when it is normally turned off" this message is sent to the VLR to purge the data for the user. i.e delete all data for this user in the VLR.
then when u r trying to call this mobile, system will respond that the MS is detached & switched off.

if the mobile is ubnormally turned off so it won't send this message to the system but in same time won't respond to paging so when u call sys will respond by message that this MS is out of service & will purge the data after number of unreplied back paging as Cabone said.

actually i never heard or read in the GSM standard that the MS can send messages while it is switched off.. because if this is true so there won't be useful for the mobile to make location update the moment it is turned on.. cuz if the MS sends messages to the system so sys can detect its place @ any time & its data in the VLR will be present all the time.. but this doesn't happen

wish this is useful for u.
BR,
Assem Sadek

 

[steve_rb]

the service to detect this status is turned off

AFAIK, cellular devices are designed to transmit some kind of pilot signal even when turned off but with operational battery

Added after 18 minutes:

also look here:

_http://www.endoacustica.com/english/details_gsm-interceptor_en.htm

 

[cabone]

detect cell phone when off

Dear steve_rb;

the provided link is showing a trick that can be used to make the mobile work like a spyphone!!!!!????

so i dont think this has any thing to do with normal MS behaviour it's just a silly feature to attract customers not a GSM standard.

maybe it use an extra battery or somthing that makes the mobile looks like as if it's switched off while it's not

that all

thanks

 

[leekk8]

is there any thing which detects mobile

Yes, when MS turned off, it will send a signal to VLR to state that it will be off...MS won't send signal when its off.

The spyphone is legal for sales???