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ISDN, SS7, V5.2 , CAS, VoIP Gateway and Signaling Converters  

LAWFUL INTERCEPTION RECORDER

Operators needing to connect their existing switches to some newer generation switches or equipment.

Focus

Lawful interception (or lawful intercept) is an action (based on the law) performed by network operators or TSPs (Telephony Service Providers), of making available certain data or voice information and providing that information to a monitoring center. Law enforcement agencies (LEA) are authorized by a law to receive the results of interceptions.

SS7 has been playing a principal role in controlling the signaling in intelligent networks for many years. This standard has been deployed globally for intelligent networks in wireline and/or wireless environments. SS7 offers a realiable source of intelligence collection. Consequently, SS7 lawful interception and tranmission of telecommunications interceptions to the monitoring center are common actions worldwide.

Solution

Telesis Stillink 3200 LIR (Lawful Interception Recorder) is a voice recorder element in monitoring center of LEAs. The applied solution is according to European (ETSI TS 101 671 V3.11.1) standards for LI (Lawful Interception). LEAs, using various network elements of multi-vendors, may consider Stillink 3200 LIR.

PSTN SS7 ISUP Intercept

Stillink 3200 Lawful Interception Voice Recorder in Monitoring Center for PSTN SS7 ISUP Intercept

 

Mobile Network SS7 ISUP Intercept

Stillink 3200 Lawful Interception Voice Recorder in Monitoring Center for Mobile Network SS7 ISUP Intercept

Implementation

Some hallmarks of the solution are:

  • Cost-effective for either TSPs or government LEAs
  • Robust, reliable hardware and firmware
  • Telesis proprietary firmware (Xymphony tailored for lawful interception recording)
  • High MTBF values
  • Web or SNMP based, easy management and provisioning
  • E1 physical interfaces to connect MDs (Mediation Devices) for recording
  • Scalability. Up to 16 E1s, 480 channel recording capacity in a single system
  • SS7 ISUP signaling on E1s
  • Flexible parameter adjustment for SS7 like point codes, CIC (circuit identification codes)
  • Up to 16 E1 SS7 link sets (1 to 16, programmable)
  • The interface model: handover interface HI3 (CC - Content of Communication)
  • Monitored and recorded HI3: unidirectional
  • Use of subaddress and UUS (User-to-User Signaling) for interception related information
  • Voice (Content of Communication) recorded transparently without any compression (64kbps, wav files)
  • Using FTP, the recorded data from the Stillink 3200 is automatically exported to a file server in advance
  • With support of dual FTP servers (primary and secondary), file transfer is warranted
  • Voice records buffering capability in case both FTP servers fail
  • Flexible file naming of intercepted voice records before exporting to FTP servers
  • Auto selection of directories in FTP server before export (related to intercept information)
  • SNMP alarm traps for E1 status
  • Generating performance metrics, statistics, and records

Information, which may be used in file naming of intercepted voice records are:

  • Any alphanumeric separator
  • Recording start date
  • Recording start time
  • Recording end date
  • Recording end time
  • Calling number
  • Called number
  • B channel number
  • Domain identifier
  • Lawful interception identifier
  • Communication identity number
  • Call identity number
  • CC link identifier
  • Operator identifier
  • Network element identifier
  • Direction indication
  • TMR (Transmission Medium Requirement)
  • High layer capability
  • Mobile bearer service code
  • Mobile teleservice code
  • Any fixed alphanumeric character set in any location

All or some of the above information may be used in file name in any sequence. Consequently, TSPs or LEAs may program their desired file naming description easily.

Reliability, Duplication, and Redundancy

The hardware and firmware of the Stillink 3200 LIR are reliable and fault tolerant solution for no loss of valuable intercept data. In addition, higher levels of system availability can be achieved via external redundancy and duplication as mentioned in reference models.

Firmware and Processing

The advanced design of the Stillink 3200 LIR incorporates state-of-the-art Industrial CPU and Digital Signal Processors that are capable of executing hundreds of millions of instructions a second. Highly efficient use of the system`s processing power, with the help of intelligent algorithms, leaves no possibility that an overload condition will arise. In the operation of the Stillink 3200 LIR, there is a sufficient margin for overload situations. Improved speed, security, and reliability are guaranteed by the placement of the generic programs and operating parameters in non-volatile semiconductor memory elements. The Stillink 3200 LIR incorporates processing units that take full advantage of the massive amount of computing power that is now available, along with the myriad of software development tools.

The Stillink 3200 LIR is a Stored-Program-Controlled (SPC) system. Its leading-edge operational software, Xymphony, has been developed by Telesis A.S. specifically for this system. With many programmable features, Xymphony makes the lawful interception recording highly efficient. Xymphony within the Stillink 3200 LIR is well structured and is developed by a high level language of C. Xymphony software provides strategies to prevent the occurrence of programming errors to escalate to present sufficient information for quick solving of the errors. The Stillink 3200 verifies the integrity of its software at regular basis.

Power System

By default, the Stillink 3200 LIR has a single solid state, high quality, robust (with high MTBF value), convectional cooling (without mechanical fans), field-proven power system. Hallmarks of this power system are:

  • Built-in active PFC function
  • Short circuit / Overload / Over voltage protections
  • Cooling by free air convection
  • 100% full load burn-in tested
  • Fixed switching frequency at PFC:67KHz PWM:134KHz
  • Overload protection: Constant current limiting, recovers automatically after fault condition is removed
  • Overvoltage protection: Shut down o/p voltage, re-power on to recover
  • MTBF 224300 hours MIL-HDBK -217F (25 )

System Resources

Although some of the Stillink 3200 LIR`s common control function is implemented in a centralized manner, many resources like digital signal processors (DSPs) are distributed. Digital signal processors provide HDLC for E1 interfaces. DSP distribution provides redundancy. All available channels from all DSPs are collected in a common pool, which is ready to serve any request within the system. In other words, in case of a failure in a DSP, its functions can be handled with other DSPs in this distributed system. The expense in this method may be concurrent call recording capacity.

HI3 (E1) and Ethernet Interfaces

External synchronization sourcing is programmable and multiple HI3 E1 interfaces may be candidates for sourcing. Intelligent algorithms within the Stillink 3200 LIR select the source among the available HI3 E1 interfaces. Consequently, loss of signal in an E1 interface does not necessarily cause the loss of synchronization. The Stillink 3200 LIR has multiple ethernet interfaces. The Stillink 3200 LIR continuously monitors ethernet interfaces for faults and warnings.

Reference Models

Different levels of system availability can be achieved via redundancy, from duplicated FTP servers to fully redundant Stillink 3200 LIR systems and FTP servers.

Single Recorder, Single FTP

The simplest level availability is a single Stillink 3200 LIR for a HI3 and a single FTP server for the records.

Single Recorder, Single FTP

 

Single Recorder, Dual FTPs

Stillink 3200 LIR supports dual FTP servers. If the primary server fails, voice records are exported to the secondary server. That provides a higher level of availability.
 
Single Recorder, Dual FTPs

 

Dual Recorders, Dedicated Single FTP

It is very easy to duplicate the voice record for the HI3 E1 interface thanks to the uni-direction of HI3. Thus, it is possible to send the same voice record to two different Stillink 3200 LIRs.  

Dual Recorders, Dedicated Single FTP

 

 Dual Recorders, Dedicated Dual FTPs 

In addition to redundant Stillink 3200 LIR for the same HI3 E1 interface, duplicating FTP servers provide the maximum level of availability.
 
 Dual Recorders, Dedicated Dual FTPs
 

Telesis A.S. 2006-2013
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