• Effective immediately we will be deleting, without notice, any negative threads or posts that deal with the use of encryption and streaming of scanner audio.

    We've noticed a huge increase in rants and negative posts that revolve around agencies going to encryption due to the broadcasting of scanner audio on the internet. It's now worn out and continues to be the same recycled rants. These rants hijack the threads and derail the conversation. They no longer have a place anywhere on this forum other than in the designated threads in the Rants forum in the Tavern.

    If you violate these guidelines your post will be deleted without notice and an infraction will be issued. We are not against discussion of this issue. You just need to do it in the right place. For example:
    https://forums.radioreference.com/rants/224104-official-thread-live-audio-feeds-scanners-wait-encryption.html

why we can not !!

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alnweer

Member
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Aug 4, 2006
Messages
9
Why can not Alastmaaali cellular phones? Operating system gsm The proprietary Alergmmen aor8200 unblocked?

Is tranche card can be opened or encrypted?

The use of certain organs? So that we can hear waves Is there any devices that could be used for this purpose? , that I have lived outside the United States
thanx for replay :)
 

KT4HX

Member
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Messages
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Location
Spotsylvania County, Va
Yes, he is from Kuwait, and he wants to be able to monitor GSM phones. Why, I don't know. I found very little to listen to on cellphones that was worth the time and effort. I don't even own any unblocked scanners anymore, and really have no desire to anymore. This is one subject that has been beat to death on here.
 

joetnymedic

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May 30, 2003
Messages
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Location
West Haven, CT
wow,
that was a different kind of message all together-LOL. Back in the day- I knew someone who had a scanner modified for the old analog cell phone systems, it was more a pain in the ass than worth it, although there was this one guy that called a phone sex line prom his car - after like a minute we were laughing so hard, it was hysterical - best part was, he didn't even make it to the girl, had to give a name, card number address, whole bunch of other stuff and all we could think of was this poor dumb schmuck slobering to some 500 lbs chicken eatin woman (or man pretending to be a woman) All the things for a good Springer show. Lost rack and couldn't hear him. We wanted to take his phone number down SOOO bad and call his wife/other half just to listen to the sparks fly. Damned that was like 25 years ago - I actually just felt young again for a sec._LOL
 

alnweer

Member
Joined
Aug 4, 2006
Messages
9
KT4HX said:
Yes, he is from Kuwait, and he wants to be able to monitor GSM phones. Why, I don't know. I found very little to listen to on cellphones that was worth the time and effort. I don't even own any unblocked scanners anymore, and really have no desire to anymore. This is one subject that has been beat to death on here.


yes friends

can i monitor the cellphone?

is there any way?
 

UPMan

Uniden Representative
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Messages
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Arlington, TX
GSM is a digital format that you cannot monitor with a scanner.
 
N

N_Jay

Guest
alnweer said:
yes friends

can i monitor the cellphone?

is there any way?
Yes, will GSM Cellular service equipment.

Expect to spend about $35,000.

No not with any consumer receiver, since GSM format is different from land mobile digital formats.
 

JohnnyGalaga

Completely Banned for the Greater Good
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Okay, so let me understand this right. GSM is TDMA and TDMA is where voice is converted to 1's and 0's and compressed, so that it only takes 1/8 of a second to transmit 1 full seconds worth of voice? That way, 8 different conversations can happen on the same frequency, with each conversation assigned to a 1/8th time slot?

Am I wrong on this ?
 

mikewazowski

Forums Manager/Global DB Admin
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Keep in mind the air interface of a GSM signal is encrypted. That fancy service monitor will show you the signalling and such but forget about voice.

You have to tap in on the T1/E1 with a test set capable of decoding the GSM audio frames. Acterna makes a dandy little unit that will show all kinds of GSM information floating across the T1/E1 including audio.
 

JohnnyGalaga

Completely Banned for the Greater Good
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So how do the cell towers know what every phone's encryption key is as phones roam around to different towers and different countries?
 

nd5y

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Messages
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Location
Wichita Falls, TX
GSM time slot length is 577 microseconds not 1/8 of a second.
As far as I know cell sites don't handle encryption and don't even decode the audio. That is all done in the Mobile Switching Centers and Authentication Centers wher the phone calls actually come out on the PSTN.

Here is another good GSM link. https://styx.uwaterloo.ca/~jscouria/trio.html
 
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N_Jay

Guest
JohnnyGalaga said:
Okay, so let me understand this right. GSM is TDMA and TDMA is where voice is converted to 1's and 0's and compressed, so that it only takes 1/8 of a second to transmit 1 full seconds worth of voice? That way, 8 different conversations can happen on the same frequency, with each conversation assigned to a 1/8th time slot?

Am I wrong on this ?
GSM uses a TDMA format for channel coding.
Binary Digital is where voice is converted to 1's and 0's
It May or May-not use compression in its coding structure.
How many seconds each frame of packet is depends on the particular format.

You are not wrong, just pulling too specific conclusions.
 
N

N_Jay

Guest
JohnnyGalaga said:
So how do the cell towers know what every phone's encryption key is as phones roam around to different towers and different countries?
Magic, (or good planning).
I am no GSM expert, but usually the key is generated using a shared secret. (Authentication code).
 

mikewazowski

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N_Jay said:
Magic, (or good planning).
I am no GSM expert, but usually the key is generated using a shared secret. (Authentication code).
I believe you are right but I'm not 100% sure. I do know that there are two ciphers used depending on the country. A51 is the stronger of the two while A52 is the weaker.

The encryption is setup between the base station (rbs) and the mobile equipment (me).

With a proper test set, you can actually decode the audio frames right at the base station.

Half rate channels are available which I guess could be considered a form of compression. With the new adaptive multi rate vocoders, half rate audio doesn't sound half bad and is starting to be implemented on busy sites.
 
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