Catalyst Introduces Intellilink™ Interworking – Innovation in LMR LTE Communications for FirstNet™

Standards Compliant solution enables communications between MCPTT devices on LTE Networks including FirstNet™ and legacy Land Mobile Radio subscriber units

Catalyst Communications Technologies, a leader in mission critical dispatch, interoperability, and incident command solutions to the First Responder community, today announces a new platform that enables Land Mobile Radio subscribers to communicate with users of Mission Critical Push to Talk applications on LTE Networks through standards compliant interfaces. IntelliLink™ Interworking leverages Catalyst’s 20 years’ experience with sophisticated radio control and interface technology with new development using the 3GPP Standards to interface to LTE Networks, including FirstNet™. The result is the first interworking solution in the market based upon these standards and follows the industry trend toward standards-based solutions and away from today’s profusion of incompatible PTT over cellular solutions.

A Migration to FirstNet™ for P25 – and everyone else

 Interworking is the term for communications interoperability between Land Mobile Radio devices used by First Responders today and new Mission Critical Push to Talk applications on mobile phones running on LTE Networks including FirstNet™. Interworking has long been considered a key component of FirstNet™ adoption, as public safety organizations will need a migration strategy as they and allied agencies move to FirstNet™. They will require simultaneous dispatch and device to device communications between LMR and LTE during the transition.

Industry groups are working on an Interworking approach based on the Project 25 (P25) Inter Sub System Interface (ISSI) standard for the LMR interface and the 3GPP MCX standard for LTE. While that model may be appropriate for many larger agencies, the cost will be high and the low deployment rate of ISSI will make it impractical for the broader market of public safety organizations. These organizations, many with older technologies, will also need an interworking solution to migrate to FirstNet™. Catalyst’s Intellilink™ Interworking solution is flexible and will support a wide variety of LMR radio networks. Catalyst’s IntelliLink™ Interworking Solutions roadmap provides a vision for how interworking will likely develop and how Catalyst plans to augment existing efforts to define a P25 ISSI to LTE interface with a solution that also enables other LMR technologies. This includes other standard LMR interfaces such as the P25 Common Air Interface (CAI) and Digital Fixed Station Interface (DFSI), the Digital Mobile Radio (DMR) Application Interface Specification (AIS), analog FM, as well as proprietary radio protocols including Smartnet™, EDACS™, and Nexedge™.


As part of the overall IntelliLink™ Interworking solution, two simple user interface platforms for managing Interworking talk groups and channels are provided, both “infinitely” configurable.  One of these tools is for Interworking only and one is a complete Mission Critical Dispatch Console for both LTE and LMR.

Development History – a Department of Homeland Security Initiative

In 2018, Catalyst was awarded a contract by the United States Department of Homeland Security (DHS) Science and Technology Directorate (S&T) to investigate standards-based Interworking that will enable mission critical communications between First Responders using Land Mobile Radio (LMR) systems and cellular devices over Long Term Evolution (LTE) Networks with push to talk applications. This contract was the result of a Small Business Innovation and Research program solicitation won by Catalyst in competition with other businesses. DHS S&T was interested in technology and solutions that take advantage of existing standards in P25 LMR and 3GPP (3rd Generation Partnership Project) LTE technologies to create seamless communications between users on these systems.

With the announcement in April 2019 that Catalyst had been awarded a Phase II, $1.0 million contract from DHS S&T to develop a prototype based upon the results of the Phase I research, Catalyst has firmly established its position as a leading contributor to the maturation of FirstNet™ and other next generation critical communications services based upon LTE technology. Today’s announcement of IntelliLink™ Interworking Solutions is the first public unveiling of the Phase II research and prototype development efforts from this program.

The Compelling Requirement for a Standards Based Solution

FirstNet™ and the First Responder community are committed to standards-based interfaces for both LMR and LTE networks to enable communications between Mission Critical Push to Talk devices on these networks. Catalyst IntelliLink™ Interworking Solutions are a complete departure from existing “Over the Top” PTT over LTE solutions because:

  • We are compliant with the MCPTT Standard, not “almost mission critical”.
  • True MCPTT provides the performance that Public Safety needs (minimal delay, protecting against lost syllables and words, and meta data).
  • True MCPTT can be integrated with the carrier’s broader solution so that, for instance, subscribers can manage their device so that PTT audio is not lost when someone places a telephone call to their cell phone.

The Catalyst approach best meets the needs of Public Safety including:

  • Catalyst’s technology protects against dropped syllables and hung channels.
  • Catalyst’s standards-compliant console provides a high level of symmetry to what First Responders are currently receiving, including Unit ID, Alias, and Emergency Indication from users on both networks.
  • Catalyst’s radio interface technology supports a wide array of LMR radio systems, not just ISSI.
  • Catalyst provides an intuitive User Interface for managing Interworking that does not require a Catalyst console.

To complement our extensive technology and knowledge of Land Mobile Radio networks, Catalyst partnered with Softil Communications Services for key technology relating to the 3GPP MCPTT/MCX Standard interface for LTE Networks. Catalyst chose Softil’s BEEHD suite of development tools after a comprehensive review of available technology to interface to LTE, concluding Softil is best in class. Softil’s MCPTT BEEHD Framework offers Mission Critical Communication solutions including Mission Critical Push-to-Talk (MCPTT), Push-to-Video, and other emerging applications for the First Responder community. BEEHD is a cross-platform client SDK designed for developers like Catalyst, looking to accelerate the development of IP-based communications over LTE for mission-critical applications.

To promote the various Interworking solutions, Catalyst has branded IntelliLink™ Interworking with a new graphic to identify Interworking Solutions. Catalyst expects that the technology developed in support of the DHS S&T Award will produce a family of products solving specific Interworking problems, promoted and identified under the new Intellilink™ Interworking brand.

Interworking Logo

The design captures a popular symbol of the first responder community and the interaction between LMR, Catalyst, and LTE.


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