Why Radios Still Don’t “Talk to Each Other”
And Why Interoperability Requires Purpose-Built Gateways
Modern communications systems are more capable than ever.
We have multiband P25 radios.
We have LTE mission-critical push-to-talk.
We have trunked systems, ISSI links, satellite backhaul, encryption, and RoIP architectures.
And yet during incidents, the same question surfaces:
“Why can’t these radios just talk to each other?”
The answer is not funding.
It is not a lack of modernization.
It is architecture.
Radios were engineered for performance, governance, and security within their own systems. They were never engineered for universal interoperability across systems.
Capability does not equal compatibility.
A VHF radio cannot receive 800 MHz RF energy.
A P25 radio cannot decode DMR vocoder traffic.
A trunked talkgroup cannot directly speak to a conventional channel.
An AES-encrypted net cannot simply merge with a differently keyed system.
These are not administrative barriers.
They are engineering boundaries.
Understanding that distinction is essential for leaders responsible for mission continuity.
The Engineering Barriers to Interoperability
Radios do not interoperate for layered technical reasons:
- Frequency band separation
- Digital modulation and protocol differences
- Trunked vs. conventional control logic
- Encryption domains and key management
- Half-duplex arbitration vs. IP full-duplex behavior
- Governance and system authorization
Each layer creates segmentation.
Frequency and RF Architecture
RF front-ends are band-specific by design. Filters, LNAs, mixers, and power amplifiers are tuned to defined spectrum allocations.
Even multiband radios achieve flexibility by embedding multiple RF chains. They do not merge spectrum. They contain separate hardware paths.
Without an intermediary operating in both bands, VHF and 800 MHz systems remain isolated.
Digital Protocol Differences
Even within the same band, digital radios may be incompatible:
- P25 Phase 1 and Phase 2
- DMR
- NXDN
- LTE PTT
Each uses different framing, vocoders, and signaling.
Digital standards were optimized for efficiency, spectrum management, and governance. They were not designed for cross-decoding at the air interface.
Trunked vs. Conventional Systems
Trunked systems rely on:
- Control-channel logic
- Dynamic channel assignment
- Talkgroup IDs
- Authentication
Conventional systems expect fixed frequencies and carrier detect.
Even when operating in the same band, a trunked talkgroup cannot directly communicate with a conventional channel without console integration or a donor-radio bridge.
Crossband Repeaters: Useful, Not Comprehensive
Crossband repeaters retransmit RF from one band to another.
They work when:
- Both systems are conventional
- Both are analog
- No encryption boundary exists
- No trunking logic is involved
They do not authenticate to trunked systems.
They do not reconcile encryption domains.
They do not manage talk-groups.
They do not arbitrate multi-network half-duplex collisions.
Crossbanding solves spectrum translation.
Interoperability requires system translation.
Why Multiband Radios Do Not Eliminate the Problem
Multiband radios reduce device burden.
They do not remove architectural boundaries.
A multiband radio must still be:
- Programmed
- Authorized
- Credentialed
- Properly keyed
Agencies do not universally distribute trunked credentials.
Encryption keys are controlled assets.
Broadband PTT operates in a separate IP domain.
Multiband improves flexibility.
It does not unify systems.
Encryption: The Invisible Wall
Modern communications span multiple cryptographic domains:
- AES-256 over RF
- TLS-encrypted SIP signaling
- SRTP media streams
- Secure Bluetooth links
- FIPS-validated firmware boundaries
Each domain is intentionally isolated.
Interoperability across encrypted systems requires either:
- Shared key infrastructure
- Console-level integration
- Or donor-radio bridging
Security and interoperability MUST COEXIST.
The Proven Method: Donor Radio Bridging
The most reliable, governance-compliant interoperability method remains simple:
One donor radio per net.
Each donor radio:
- Authenticates natively on its home system
- Uses its own encryption keys
- Operates within its assigned band
- Respects trunking governance
The gateway bridges audio at the baseband layer — after each radio has completed its native RF, authentication, and encryption functions.
No infrastructure changes.
No encryption key sharing.
No trunked system reconfiguration.
No expanded credential exposure.
This model preserves system integrity while enabling operational flexibility.
It works:
- At scene
- In a mobile command vehicle
- In a fixed EOC
- As a permanent interoperability core
Because it respects boundaries rather than attempting to erase them.
Where ICRI Operates Differently
The Incident Commanders’ Radio Interface (ICRI) is built around this donor-radio architecture. It is designed to scale from tactical deployment to enterprise integration.
It respects system boundaries.
It preserves encryption governance.
It keeps control with the agency.
No Encryption Key Required
ICRI does not require access to trunked encryption keys.
Each donor radio remains fully responsible for:
- System authentication
- Talkgroup affiliation
- Native encryption
- Key management
ICRI does not decrypt trunked traffic. It bridges audio only after native cryptographic functions are complete.
This preserves:
- System security boundaries
- Key control policies
- CJIS and federal compliance
- Agency governance autonomy
The architecture supports segmented trust models at both tactical and enterprise levels without expanding key exposure risk.
Rapid Reconfiguration as Conditions Change
Incidents evolve.
Agencies arrive.
Agencies demobilize.
Operational priorities shift.
Interoperability must adjust in real time.
ICRI allows operators to:
- Add or remove donor radios quickly
- Create or break patches instantly
- Isolate nets when needed
- Reassign communications paths as command structure evolves
There is no need to:
- Reprogram trunked systems
- Wait for console changes
- Request system administrator intervention
- Modify encryption key sets
At the tactical level, this means immediate adaptability at scene.
At the enterprise level, it allows EOCs and regional coordination centers to dynamically manage interoperability without changing underlying infrastructure.
Flexibility is built into the hardware - not dependent on software permissions or subscription models.
Operational Control at Scene or Systemwide
ICRI places interoperability authority directly in the hands of command.
The Incident Commander determines:
- Which radios are bridged
- Which nets remain isolated
- Who talks to whom
- When connections are created or removed
That same control model can operate within:
- A fixed EOC
- A regional coordination center
- A statewide emergency operations environment
No reliance on console reprogramming.
No trunked core changes.
No recurring service layers.
Control remains local.
Authority remains with the agency.
Alignment with National Interoperability Frameworks
ICRI aligns with recognized national interoperability doctrine.
SAFECOM Interoperability Continuum
Supports Technology and Usage lanes with repeatable, governance-aligned interoperability — deployable tactically or as a fixed core.
NIST Cybersecurity and Resilience Guidance
Respects cryptographic boundaries and segmented trust models without centralizing key control.
National Mutual Aid Doctrine
Enables interoperability across jurisdictions without assuming shared infrastructure or shared credentials.
It supports resilience planning at both the incident and enterprise level.
Enterprise Integration vs. Tactical Control
Enterprise interoperability platforms integrate systems across regions.
They often require network management layers, centralized infrastructure, and recurring service models.
ICRI delivers the same core bridging functions — band-to-band, trunked-to-conventional, LMR-to-LTE — without requiring servers, subscription fees, or infrastructure dependency.
Portable.
Infrastructure-independent.
Scalable to fixed installations.
Controlled at scene or systemwide.
It does not replace enterprise gateways.
It gives agencies the option to deploy interoperability at the tactical edge or within the enterprise — on their terms.
When infrastructure is unavailable, saturated, or constrained, interoperability must still function.
Infrastructure integrates networks.
ICRI empowers command.
Interoperability Is Not Accidental
Radios do not fail to talk because agencies failed to modernize.
They fail to talk because:
- They were engineered differently
- They operate in different governance domains
- They protect different encryption boundaries
- They rely on different transport architectures
Interoperability is not about forcing systems to merge.
It is about bridging them intelligently.
2026 Top 15 Donor Radio Reference
For agencies evaluating interoperability readiness, we have compiled:
“2026 Top 15 Donor Radios Commonly Used with Interoperability Gateways in the USA.”
This reference reflects current fleet prevalence across:
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- Public Safety
- Commercial and Utility
- Auxiliary and Volunteer operations
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📎 Download the 2026 Top 15 Donor Radio List
At the incident scene, command clarity matters more than architectural purity.
Infrastructure may vary.
Encryption may differ.
Bands may conflict.
The Incident Commander still needs control.
If you are evaluating interoperability strategy for 2026 and beyond, ensure your solution does not just connect systems.
Ensure it empowers command.
OWN THE COMMS. Own the bridge.
Interoperability without compromise.