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Lawful Interception Software

VOCAL provides Lawful Interception software solutions for voice, fax/facsimile and data communications. Our lawful interception software libraries are used to decode fax transmissions from previously recorded files or real-time sniffer sources intercepted over PSTN and IP networks. As a leading lawful interception software company, our expertise in the design, implementation and configuration of fax, VoIP, network, and telephony products will help you develop your lawful intercept application quickly and efficiently. Contact us to discuss lawful interception requirements for your application.

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VOCAL’s lawful interception software library is modular and optimized for DSPs and conventional processors from TI, ADI, ARM, AMD, Intel and other leading vendors.  Our software may be licensed as a library or complete solution. Custom designs are also available to meet your specific lawful interception requirements.

Lawful Interception of Fax/Facsimile

VOCAL’s Lawful Interception software provides a fax monitoring module with a fax demodulator and decoder to handle both standard as well as manufacturer specific T.30 ‘Non-Standard Facilities’ (NSF) features. Blind data retrieval and consistency checks ensure accurate image recovery and avoid any compatibility issues with non-standard fax machines.

Lawful Interception of T.38 Fax over IP

VOCAL’s Lawful Interception software also includes extraction of facsimile images from previously captured T.38 Fax over IP (FoIP) network traffic or real-time sniffer T.38 Fax data streams. Our expertise with FoIP, SIP and deep packet inspection is essential for extracting the data of interest from the large volumes of VoIP traffic encountered on today’s networks. With these capabilities, developers have a range of lawful intercept software solutions for packet capture, monitor and decode of fax and data modem transmissions.

Lawful Interception of VoIP Network Traffic at an ISP

VOCAL’s voice, fax and data intercept solutions may be operated standalone or as part of a distributed system where the intercepted information is captured and distributed by a gateway to the authorized law enforcement destinations where it can be decoded and interpreted. The architecture below illustrates a reference model for implementing a lawful intercept packet capture solution of Voice over IP (VoIP) network traffic at an Internet Service Provider.

VoIP Lawful Interception at Network ISP

Lawful Interception Gateway delivers VoIP network traffic captured at an IAP to the LEA

The law enforcement agency (LEA) sends a request to the system administrator. Based on the authorized level of access for the LEA and the request, either the lawful intercept related information (IRI), content or both is then collected by the respective intercept access point (IAP) and delivered by the lawful interception gateway (MD) to the LEA for processing.

Typically, automatic sniffer programs intercept data at access points on the digital segments of PSTN and on IP networks at routers and switches using port mirroring or network taps to capture the packet data at network speeds. Either method duplicates and diverts the packets without interfering with the original data stream. Either the entire data stream or of only those packets that satisfy the frame capture filter criteria are recorded by the lawful interception system for processing.

When the initial call information is placed, the system can detect the event and record this information as the IRI. If the LEA is only authorized to receive the IRI, this information is passed to the LEA along with any other lawful intercept related information. If the call information is to be collected, the IRI will contain information, such as the IP address and encoding scheme, needed to find and track the call session.

Lawful Interception Requirements

Most nations have some requirement for lawful interception compliance and reporting standards that service providers must satisfy. In the United States, the Communications Assistance for Law Enforcement Act (CALEA) requires telecommunications companies including common carriers, broadband Internet access and Voice over Internet Protocol (VoIP) service providers, to support lawful intercept efforts.

Requirements may vary across national and even state boundaries. Service providers must:

  • Understand their obligations for each jurisdiction in which they operate.
  • Coordinate intercepts with other providers and network operators.
  • Handle targeted individuals that temporarily access their own network.
  • Adjust or even suspend collection activities as the person of interest crosses jurisdictional boundaries.

Because of the sensitive nature of lawful intercept, there are basic requirements which need to be met.

  • Access Control: Only authorized entities should be allowed to access collected information. Also, there may be restrictions on WHAT information is to be passed to the LEA (for example, only the caller information). Finally, undelivered information must be kept in such a way that if power is lost, that information is destroyed.
  • Encryption Keys: Any encryption keys known by the service provider must also be passed to the LEA. In case of end-to-end encryption (i.e. using a key unknown to the service provider), the entire intercepted packet must be delivered.
  • Secrecy: The interception must be done in such a way that the subject of interest is not aware of the interception taking place.


supported platforms

VOCAL’s optimized software is available for the following platforms. Please contact us for specific lawful intercept software supported platforms.

ProcessorsOperating Systems
  • Texas Instruments – C6000 (TMS320C62x, TMS320C64x, TMS320C645x, TMS320C66x, TMS320C67x), DaVinci, OMAP, C5000 (TMS320C54x, TMS320C55x)
  • Analog Devices – Blackfin, ADSP-21xx, TigerSHARC, SHARC
  • PowerPC
  • MIPS – MIPS32, MIPS64, MIPS4Kc
  • ARM – ARM7, ARM9, ARM9E, ARM10E, ARM11, StrongARM, ARM Cortex-A8, Cortex-M1
  • Intel / AMD – x86, x64 (both 32 and 64 bit modes)
  • Google Android
  • Apple iOS / iPhone / iPad & MacOS
  • Unix,  Linux, μClinux, BSD
  • Microsoft Windows ACM / RTC / CE / Mobile
  • Symbian
  • eCOS / eCOSPro
  • Wind River VxWorks
  • Green Hills Integrity
  • Micrium μCOS
VOCAL Technologies, Ltd.
520 Lee Entrance, Suite 202
Amherst New York 14228
Phone: +1-716-688-4675
Fax: +1-716-639-0713