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IntelliLink™ Interworking

IntelliLink™ Interworking is the first interworking solution that is compliant with standards-compliant interfaces on both the Land Mobile Radio (LMR) and public cellular Longterm Evolution (LTE) networks . This includes FirstNet™, Verizon’s public safety core, and other networks that support Mission Critical Push to Talk (MCPTT) applications.

IntelliLink™ Interworking is an interworking solution that provides communications between subscriber units on existing public safety LMR networks with new first responder subscribers using MCPTT applications on 3RD Generation Partnership Project (3GPP) compliant LTE cellular networks, including FirstNet™. IntelliLink™ Interworking is unique because it will augment existing efforts to define a Project 25 (P25) Inter SubSystem Interface (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 LTR , EDACS™, and Nexedge™.

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™. These agencies will require simultaneous dispatch and device to device communications between LMR and LTE during the transition.



IntelliLink Interworking leverages Catalysts’ expertise in managing radio communications across Internet Protocol (IP) networks. Catalyst technology is superior to other solutions because it manages the flow of audio between two radio systems to guard against lost audio.

Catalyst provides an advanced interface to legacy control stations such as EDACS™, LTR, etc., and modern control stations (DMR, P25, NXDN), and to the wireline interfaces for DMR, P25, and LTE. When talk groups on the two systems are connected using IntelliLink™ Interworking, Catalyst buffers the audio until the target radio system is ready to re-transmit it so that the complete transmission is routed between the legacy system and the new one. Rather than VOX or COR, Catalyst uses the digital messages, when available, from each system to know when each call starts and stops, creating a more reliable interoperability solution. IntelliLink™ Interworking also creates an electronic record of every call to and from both systems so that the System Administrator can review the call flow after an incident.

Key Features

IntelliLink™ Interworking is a standards compliant solution, designed to deliver the mission-critical voice communications traditionally transmitted via LMR systems to users communicating across LMR and LTE networks. This level of robustness is required by first responders seeking to introduce LTE based mission critical push-to-talk communications into their operations.

Standards Compliant Interfaces

IntelliLink™ Interworking interfaces to LTE Networks that support MCPTT through a 3GPP standard interface. The LMR radio interfaces can be flexibly assigned. In addition to the P25 ISSI interface, IntelliLink™ Interworking will interface to P25 systems through DFSI, to Digital Mobile Radio (DMR) systems through the AIS interface, and to other legacy radio systems through Catalyst’s family of analog and digital control station interfaces.

Simple and Intuitive Interworking

For selecting LMR and LTE talk groups and LMR channels, a simple user interface is provided so that communications between these entities is easily established. A dispatch console is not required. As another option, choose to incorporate IntelliLink™ Interworking technology into Catalyst’s IP|Console™ and Propulsion™ Dispatch Consoles for a single user experience that manages LMR to LMR Interoperability and LMR to LTE Interworking.

A DHS Funded Initiative

In 2018, Catalyst was awarded a Phase I contract by the United States Department of Homeland Security (DHS) Science and Technology Directorate to investigate standards-based Interworking that would 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. With the announcement in April 2019 that Catalyst had been awarded a $1 Million Phase II contract from DHS S&T to develop a prototype based upon the results of the Phase I research, Catalyst began development of a comprehensive solution. IntelliLink™ Interworking is the first product developed from this program.