Fig.1 Main Screen The main operation screen is divided into 4 main parts:
- receivers window
- tape recorder window
- target list/base stations list
- protocol window |  |
Fig.2 Receivers window
1.Receiver number
2.Channel/Timeslot number
3.Receiver status
4.Traffic channel
5.Signal level indicator of forward and reverse channels 6.Identity of intercepted call or name of the network operator
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Fig.3 Receivers setup screen
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Fig.4 Target List |  |
Fig.5 Target List Edit window | |
Fig.6 Base Stations List |  |
Fig.7 Tape Recorder Window
1. Receiver number
2. Voice Record Level Indicator
3. TMSI or IMSI number
4. Duration
5. Reset Call button
6. Pause button
7. Speaker ON/OFF button
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Fig.8 Protocol window |  |
Fig.9 Toolbar |  |
The system has 3 main operational modes:
1. Random mode
2. Classmark mode
3. IMSI/TMSI mode
Only one of these main modes can be chosen and used at any given time.
In addition the system has 4 more operational modes:
4. Distance mode
5. Phone number mode
6. Reverse channel mode
7. IMEI mode
The additional operational modes are used together with main modes. The additional modes can be used together in any combination.
2.1 Main Operational modes
2.1.1. Random mode
This mode is usually used to intercept all calls to or from a given area if the particular phone number is unknown.
2.1.2. Classmark mode
All mobile phone are distinguished by their classmarks. The classmark is one of the characteristics of mobile phones which is never changed. As soon as some phone conversation is intercepted the classmark of the active phone is displayed in the protocol window and can be put on the target list. Subsequently this parameter can be used for monitoring calls made from or to the specific mobile phone.
2.1.3. IMSI/TMSI Mode
The real mobile phone number is never transmitted over the air in GSM networks. Instead of phone numbers GSM networks use special identities (IMSI or TMSI) for mobile phone authentication.
Using a special technique the system discovers the identity that corresponds to the particular phone number. These identities are stored in the target list and used for monitoring by specific phone number (see Fig.5).
One of these identities (TMSI) is changed from time to time. The system automatically follows all TMSI modifications and automatically updates them in the Target List without intervention by the system operator.
2.2 Additional Operational Modes
2.2.1. Distance mode
This mode allows interception of those conversations, and only those conversations, being made to or from mobile phone located at a given distance from Base Stations. The distance can be specified in the Receiver Setup Screen (see Fig.3).
This mode may be used effectively when there is some "Place of Interest" and there are no particular phone numbers or other information about mobile phones for that place.
2.2.2. Reverse Mode
When reverse mode is active only conversations with active reverse channel (i.e. from mobile phones located near the interceptor) will be intercepted.
This mode can be very useful for the interception of calls being made to or from a specific area when the interceptor is in the area.
Another very effective implementation is a combination of (main) Random Mode and (additional) Distance and Reverse Modes together with a uni-directional antenna. In this case a "Place of Interest" can be defined very closely in terms of distance from one side and by azimuth from he other side.
2.2.3. Phone Number Mode
When this mode is active the only calls intercepted will be calls made from or to a phone number defined in the Target list (see Fig.5 Target List Edit window).
2.2.4. IMEI Mode
Some GSM networks use IMEI identity. This parameter can be very useful as it is a characteristic
of mobile phones which is never changed.
In addition this identity contains the model of the mobile phone. If IMEI is used by the GSM network, Interceptor will display models of mobile phones in the Protocol Window.
3. Effective Radius
The Inteceptorґs effective radius may depend on the direction of transmission. In mobile communication there are two directions:
* The direction outward from a base station to a mobile phone is considerd the forward channel.
Normally the system can intercept traffic in the forward channel at a distance of 3 to 10 km
and even more because a signal in the forward channel is strong.
* The opposite direction from a mobile phone to base staion is considered the reverse channel.
Normally the system can intercept traffic in the reverse channel at a distance of only 100 to 600 meters because a signal in the reverse channel is significantly weaker. The exact effective radius for the reverse channel depends on many factors including walls and their thickness, relative positioning of the system and mobile phone, terrain and more.
As long as base station transmitters and mobile phone transmitters differ in power the effective radius of the Interceptor will differ according to channel, but in order to hear both sides of the conversation, the Interceptor needs to be close enough for the weaker channel - normally 600 meters or less.
However, the Interceptor can also be used as a stationary device with uni-directional antennae. In this way the effective radius for the reverse channel may be increased to as much as 1,000 meters.
4. How to choose the right configuration
Although the obvious answer and often the best is "the more channels the better", still various factors such as budget may make this guideline less useful in practice. For choosing a price/performance level there are three main performance considerations:
1. Ability not to miss calls
2. Ability not to miss a more important call than the one currently being intercepted
3. Ability to intercept simultaneously numerous calls
Letґs analyze each of those.
4.1 Ability not to miss calls |
| At the beginning of interception all existing receivers dedicated to forward channels must be tuned to the nearest-to-target-phone-base-stations. Depending on its environment a mobile phone can communicate with a GSM network via one of several preferred base stations located nearby. | |
In Fig.1 the mobile phone may choose among 4 base stations so the interceptor needs at least 4 forward receiver channels. If an Interceptor with forward receiver channels is used in this situation the chances of missing the call will be around 50%.
4.2 Ability not to miss a more important call than the one currently intercepted
This is another important feature of the Interceptor. Suppose some call is intercepted. One of the forward receiver channels is then receiving voice traffic of one of the base stations and, if there are no additional free receivers, cannot monitor other calls of the base station. Therefore one of the preferred base stations is not under surveillance. If at this stage another call occurs that is more important, it cannot be missed. For that reason it is very important to have a surplus of forward receiver channels over the number of preferred base stations.
4. Number of simultaneously intercepted calls
For this model of the Interceptor the number of reverse channels is usually equal to the number of forward channels. One of our standard models has 4 forward and 4 reverse channels. In practice this means that such an Interceptor can monitor and record four conversations simultaneously (including both sides of the conversation).
The Interceptors can be produced and supplied in various configurations depending on customer needs and budget.
The following system configurations are standard:
2+2, 3+3, 4+....8+8.
(2+2) means that the system has four receiver channels: two forward channels and the other two reverse.
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System features:
1.) The system covers GSM 900 -1800/1900 Mhz bands.
2.) The system acquires the IMSI, IMEI, TMSI, Class mark, dialed and received numbers info from the GSM network
3.) The system obtains vital information pertaining to the GSM network such as encryption, frequency-hopping sequence in use
4.) The system monitors calls both in encrypted (secure) and frequency hopping modes depending on the network status.
5.) The system extracts all the necessary vital information pertaining to the target GSM network from off the air interception and configures the system so as to be able to monitor any selected subscriber from the database.
6.) The system caters for handling all variants of standard authentication, cipher key generation and encryption algorithms.
7.) The system intercepts and records SMS messages from and to the targeted mobile numbers in Microsoft Word format
10.) The system interrogates the selected subscriber from the database to ascertain/confirm a target subscriber’s identity
11.) The system is available in various configurations. It is also possible to configure the system for monitoring in duplex or simplex mode or a mix of both depending on user choice at the time of order.
12.) The system determines the outgoing number dialed by a mob subscriber.
13.) The system monitors duplex communication of mobile subscriber in both mobile originated and terminated calls.
14.) The system can also work on 12 VDC, car cigarette lighter for operational use.
15.) Auto detect, decoding and recording to the digital media (magnetic / optical) of telephone conversations in the system.
16.) Scanning of GSM network parameters in the controlled area (Service Provider ,Channel No., LAC, Cell IDs, Signal Levels).
17.) Several systems can be configured in a LAN environment to provide a near-exact physical location of the target and to form a Central Monitoring Station.
18.) Showing and recording to the magnetic media of the protocol of telephone conversations and other events in an inspected zone of a communication system with sorting by numbers and dates.
Performance Features:
(a) Monitoring Range:
The system monitoring range is 15 Km's or greater with the help of directional antenna.
(b) Encryption :
The system online decodes A3, A8 & A5, A5.1 and A5.2 algorithm variants.
(c) Scanning Abilities:
(I) The system is able to scan the entire cellular phone activity within its range to identify potential targets.
(II) The system has the capability to listen in all the simplex/duplex channels as per configuration and records all of them simultaneously.
(III) The system has the capability to monitor many base stations simultaneously.
(IV) The system provides more than 100 numbers of subscribers for targeting.
(V) The system provides subscribers identification based on MS, ISDN, IMSI, TMSI, IMEI & Class mark.
System software features:
(A) Operating System : Win9x/2000 NT 4.0 /XP
(B) The system displays the following data:-
(I) Calling and called numbers
(II) Call originator-base station or mobile
(III) Type of encryption used.
(IV) TMSI, IMSI, IMEI, Class mark, distance of the target from BTS and dialed/received numbers
(V) Start/End date and time of intercepts.
(VI) Mobile network operating in the area with their characteristics e.g. code numbers, authentication, enciphering and freq hopping in use.
(VII) Network paging and handover information’s.
(C) The system provides scanning ability to identify potential targets in the area.
(D) The system provides simple to use targeting system. Ability to target a mobile based on its number, ISDN/IMSI/TMSI/IMEI/class mark.
System Configuration:
(A) Packing is available in Single suitcase /briefcase.
(B) PC: Laptop type, with CD writer, ruggedised for field usage.
System Electrical Specifications
(A) Acceptable Voltage : 180 to 240 V AC /12 V DC
(B) Acceptable Freq. Range : 47 -53 Hz
System Environmental Specifications
(A) Operating Temp. : 0 to 50 deg C.
(B) Storage Temp : 0 to 50 deg C.
System Mechanical Specifications
Shock resistance is adequate to withstand effects of repeated vehicular transportation.
Reference features of each system are:
(I) Possibility of round-the-clock operation in an auto mode without the operator involvement.
(II) Simplicity of maintenance which does not require a deep knowledge, either in the field of computers, or in the field of cellular communication systems.
(III) Provision of reliable reception of the information from channels of cellular communication systems with possibilities of noise-resistant coding.
(IV) Usage in the hardware of systems of element base of the world leading manufacturers Motorola, AT&T, Bell Labs, Lucent, Maxim, Intel, Hitachi, Atmel, National Semiconductor, Texas Instruments.
(V) Highest reliability of the equipment.
 | Monitoring radio frequency cellular channels. |
| | Encrypted cellular systems tracking with a priority unknown keys. |
| | Automatic selection of indicated cellular phones for control. |
| | Selection possibility by distance from cell to target phone. |
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| Recording and storage of all information on PC hard disk or external storage. |
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