Trunking 2.5 – Scalable, Smart, and Spectrum-Efficient
KENWOOD's next-generation TDMA Digital Trunking solution, engineered for customers who demand more flexibility from shared frequency systems without sacrificing reliability or performance. Designed to dynamically allocate two simultaneous talk paths per 12.5 kHz channel using TDMA, Trunking 2.5 enables seamless voice and data communications across single-site or multi-site configurations.
Unlike traditional trunking systems that require dedicated control channels, Trunking 2.5 introduces intelligent control channel hibernation and rotation, maximizing frequency efficiency in environments where spectrum availability is limited. Trunking 2.5 is supported in the NX-3000 and NX-5000 series of flexible, multi-protocol radios—offering a dependable and future-ready path to expanding your enterprise-grade communications.
Hardware: TKR-2500 Repeater & KTI-2500 System Controller
Trunking 2.5 is built on a foundation of intelligent, IP-based hardware. At the core are two key components: the TKR-2500 repeater, which provides the RF infrastructure and embedded control logic for single-site systems, and the KTI-2500 system controller, which extends functionality to support larger, multi-site networks.
TKR-2500 Repeater
The TKR-2500 is the foundation of every Trunking 2.5 system. It combines high RF performance with an embedded controller, making it ideal for single-site deployments with up to six repeaters. Each unit supports voice, GPS, and fallback logic, and is easily managed over IP.
Models:
- TKR-2500VM: 136–174 MHz, 50W
- TKR-2500UM: 470–520 MHz, 40W
- TKR-2500UM2: 400–470 MHz, 40W
Key Specifications:
- Embedded controller for up to 6 repeaters
- Continuous duty cycle
- RX Sensitivity: –122 dBm
- Selectivity: 85 dB (VHF), 83 dB (UHF)
- Intermodulation Rejection: 80 dB
- Blocking: 113 dB
- Web browser configuration
- Remote monitoring via IP
KTI-2500 System Controller
The KTI-2500 is required for systems with more than 6 repeaters or for multi-site deployments. It enables advanced features like G.711 SIP voice, alternate GPS slot, OTAP, redundancy, and multi-site control.
Key Features:
- Controls up to 16 sites
- Manages 8 repeaters per site (48 channels maximum)
- Web GUI for configuration
- OTAP (Over-the-Air Programming)
- SIP telephony integration
- GPS slot for fast location polling
- DES encryption
- SNMP, RADIUS, LDAP integration
Includes:
- 1 license each for AIS Console + SIP Phone
- High Availability License for redundancy (KWD-2500HAK)
System Configurations
Trunking 2.5 supports multiple system designs, from small single-site operations to regional multi-site networks. Whether using embedded controllers or centralized management, every setup leverages IP-based communication and requires no sync cabling.
Single-Site System (Embedded Controller)
Perfect for campuses, hospitals, and small industrial sites.
- Up to 6 TKR-2500 repeaters
- 12 talk paths (2 per repeater)
- No external controller required
- Web-based configuration and monitoring
Single-Site System with KTI-2500
Ideal for sites with heavier traffic or integrated dispatching needs.
- Up to 8 TKR-2500 repeaters
- 16 talk paths
- Expanded advanced features: SIP, GPS alternate slot, OTAP, Redundancy
- Supports SNMP monitoring, dispatch console, logging recorder, and GPS
Multi-Site System
A single controller supports up to 16 sites, with up to 8 repeaters per site for 48 physical channels maximum per network.
- Up to 16 sites, all linked via IP (no sync cables)
- 8 repeaters per site (48 channels max)
- Controller can be centralized or remote
- Supports data services, monitoring, and redundancy
Logical Channel Types
In Trunking 2.5, each “channel” refers to a logical time slot on a 12.5 kHz TDMA frequency. These time slots are dynamically assigned by the system to handle voice, data, GPS, and signaling traffic. Each TKR-2500 supports two TDMA time slots per RF channel, and channel types are dynamically allocated and managed by the controller to maintain continuous system efficiency.
Control Channel
Handles signaling between the network and subscriber radios. Identifies the system, processes call requests, and coordinates traffic assignments.
- Manages talk group setup and teardown
- Used for registration, affiliation, and call grant signaling
- Can be dynamically rotated or hibernated to preserve spectrum
Traffic Channel
Used for actual payload, including voice, GPS data, and short messages.
- Carries user communications (voice and data)
- Supports packet data, AVL (Automatic Vehicle Location), and emergency alerts
- Dynamically assigned per call/session
Alternate GPS Channel (KTI-2500 only)
Dedicated slot for high-speed polling of GPS location data.
- Supports up to 1,000 location responses per minute
- Offloads location reporting from standard traffic channels
- Requires KTI-2500 controller
Operation on Shared Frequencies
Operating on shared spectrum presents unique challenges, especially when dedicated frequencies are unavailable. Trunking 2.5 is designed to work within these constraints using two intelligent strategies: Control Channel Hibernation and Control Channel Rotation. These features minimize the effects of interference, comply with FCC requirements, and ensure fair use of non-exclusive channels. Both modes can be run simultaneously, giving system administrators the tools to optimize for their specific regulatory, operational, or traffic conditions.
Control Channel Hibernation
In hibernation mode, the control channel enters a “sleep” state when not in use. It periodically wakes to provide synchronization. If a co-channel transmission is detected from another user on the same frequency, the system temporarily disables the channel to avoid interference.
- Efficient in low-traffic environments
- Improves coexistence on public/shared bands
- Automatically reassigns traffic when co-channel signal is detected
Control Channel Rotation
In rotation mode, the control channel cycles through different available channels or time slots in a predictable interval. By continuously rotating the control slot, the system ensures that no single channel is monopolized and that the trunking function remains resilient and evenly distributed.
- Ideal for moderate/high traffic environments
- Avoids long-term blocking of any single frequency
- Keeps the trunking function resilient and evenly distributed
Example: A hospital campus using shared spectrum doesn’t risk system failure due to neighboring systems. If a co-channel signal is detected—for example, from a construction crew nearby using the same frequency—Trunking 2.5’s control channel temporarily disables that channel and automatically reassigns traffic, maintaining reliable communication without interference.
Network Features & Flexibility
Trunking 2.5 is more than just a flexible trunked voice solution—it’s a modern IP-based communications platform. From dynamic site linking to SIP phone integration and remote programming, Trunking 2.5 enables advanced functionality typically reserved for larger Tier III systems, but with easier deployment and less infrastructure.
IP-Based Architecture
Every connection is managed via Ethernet—no sync cables, no analog timing requirements.
- Scales from small single-site systems to large regional networks
- Simplified installation and cabling
- Remote management and diagnostics over LAN/WAN
- Compatible with commercial network gear (routers/switches)
OTAP (Over-the-Air Programming)
With the KTI-2500 controller, radios can be reprogrammed remotely.
- Reduces downtime and service costs
- Update talk groups and features over the air
- Requires optional IP mobility router
SIP Telephony Integration
Use a SIP desk phone as part of your radio network.
- Make/receive calls between radios and phones
- Great for dispatchers, supervisors, and fixed locations
- Enables call bridging between radio and VoIP networks
- Includes 1 SIP license with KTI-2500 controller
Data & GPS Support
Packet data is supported natively, including GPS for AVL (Automatic Vehicle Location).
- GPS polling via dedicated Alternate Channel (KTI-2500 required)
- High-speed location updates: up to 1,000 locations/minute
- Ideal for fleet tracking, delivery, or safety use cases
System Redundancy & Fallback
Trunking 2.5 was designed with fail-safes and fallback modes to ensure that communication doesn’t stop, even if the network does. Controller redundancy and automatic fail-over options allow the system to recover quickly from faults, disconnections, or controller loss. All system state and health can be monitored remotely using the KTI-2500’s built-in web interface, as well as SNMP.
High Availability Mode (Optional)
KTI-2500 controllers can be paired in a mirrored configuration for redundancy.
- One primary and one secondary controller
- Automatic failover upon detection of fault
- Seamless continuity of system operation
- Requires KWD-2500HAK license
Fallback to Single Site Mode
If the IP link between sites fails, each site continues to operate locally.
- Maintains site-specific voice and data services
- Automatically reverts to full networked mode once connection is restored
- Ideal for wide-area or multi-building campuses
Control Channel Reassignment
If a control channel fails or is disabled (e.g., interference), the system moves it.
- Uses control channel rotation feature
- Can automatically reassign to backup slot
- Ensures system stays online and traffic continues
Trusted Across Industries
Whether you’re managing a multi-building hospital, coordinating logistics in a factory, or overseeing security at a stadium, Trunking 2.5 adapts to your communication needs. Its dynamic channel management and IP-based architecture make it ideal for operations where reliability and efficiency are non-negotiable.
Education
Large campuses and multi-building districts benefit from single or multi-site coverage with seamless roaming.
- Instant communication between administration, security, and facilities
- Centralized dispatch with GPS tracking
- Works on shared public safety spectrum
Healthcare
From emergency coordination to day-to-day operations, Trunking 2.5 ensures uptime.
- Resilient fallback in case of network interruption
- Integration with SIP phones at nursing stations
- OTAP ensures radios stay updated with zero downtime
Manufacturing & Logistics
Covers warehouses, plants, and distribution hubs, all from one system.
- Monitor safety protocols and team movement via GPS
- Combine voice + data to streamline operations
- Supports control channel rotation in congested RF areas
Hospitality & Event Venues
Lightweight, license-friendly systems that still deliver advanced capability.
- Coordinate front desk, security, and maintenance
- Works well with business band frequencies
- OTAP reduces support calls
Compatible Radios
Trunking 2.5 is fully supported by KENWOOD’s NX-5000 and NX-3000 series radios. These models support multiple protocols and advanced features to provide the best option for interoperability across different system types, and the durability required for demanding environments. When paired with a licensed KTI-2500 controller, they unlock the full power of dynamic control channel operation, GPS tracking, over-the-air programming, and more.
NX-3000 Series
Flexible mid-tier solution for most commercial and enterprise applications.
- VHF (136–174 MHz), UHF (400–520 MHz)
- Available with or without display/keypad
- Built-in GPS (select models)
- Requires KWD-3501TR Digital Trunking license
- Fully compatible with control channel hibernation/rotation, OTAP, GPS tracking
NX-5000 Series
Premium multi-protocol radios for enterprise and mission-critical applications.
- VHF (136–174 MHz), UHF (400–520 MHz)
- AES/DES encryption options for secure communications
- Built-in Bluetooth®, GPS, and microSD standard
- Multi-deck/multi-head configuration flexibility
- Full-color display
- KWD-5300CV DMR license included
- Compatible with OTAP, GPS, and SIP features via KTI-2500
- Intrinsically Safe (IS) options available