Which Hazardous-Area Radios Support Individual Call, Group Call, and Emergency Call?

In a hazardous industrial environment, the three basic call types are not interchangeable conveniences. Each one serves a distinct operational function, and the absence of any one of them creates a gap in the safety communication layer. A group call coordinates a crew during a routine valve isolation. An individual call allows a supervisor to confirm a permit before work begins.

An emergency call alerts every relevant person the moment a situation escalates beyond what a group call can handle. All three need to work simultaneously, reliably, and within the same device that a worker carries into a Zone 1 or Zone 2 classified area.

In Brief

Three Hytera intrinsically safe terminals support individual call, group call, and emergency call as standard capabilities. For DMR networks, the HP71XEx (IIA and IIC variants) and HP79XEx IIC provide all three call types within IECEx and ATEX certified enclosures for Zone 1 and Zone 2 hazardous areas.

For TETRA networks, the PT890Ex delivers individual call, group call, and emergency voice calling as defined capabilities within the TETRA standard, with ATEX IIC certification for the most demanding gas group environments. All three terminals operate on private network infrastructure independent of public carrier networks.

Why Call Type Completeness Matters in Hazardous Areas

A radio that only supports group calls covers team coordination but cannot reach a single person without broadcasting to everyone on the channel. A radio that supports individual calls but no emergency call function cannot distinguish a routine check-in from a life-safety alert. A radio that has an emergency button but no location reporting leaves the dispatcher knowing that something is wrong without knowing where.

In a standard office or warehouse environment, these gaps are inconveniences. In a Zone 1 classified process area, they are functional failures in the safety communication architecture.

The reason all three call types are explicitly required in professional hazardous-area radio specifications is not that they are equally useful day-to-day. Group calls handle the majority of routine operational traffic. Individual calls handle sensitive operational instructions that should not be broadcast to the full team. Emergency calls exist to override both.

DMR Path: HP71XEx and HP79XEx IIC

For organisations operating DMR trunking or conventional networks, the HP71XEx and HP79XEx are Hytera's current-generation intrinsically safe DMR portables. Both support individual call, group call, and emergency call as standard DMR call types.

The HP71XEx is available in IIA and IIC variants. The IIC variant covers Zone 1 and Zone 2 environments where hydrogen, acetylene, or other IIC gas group substances are present. The IIA variant covers lower-reactivity gas group environments such as propane-type atmospheres.

Both variants carry the same audio platform: a 2W high-power speaker, AI intelligent noise reduction algorithm, and AGC. The IIC variant operates from -25°C to +60°C in explosion-prone areas; the IIA variant operates from -25°C to +50°C.

The HP79XEx IIC is the same product generation as the HP71XEx IIC, with a 2.4-inch colour display and multifunctional buttons. The larger screen is suited to supervisory and shift-lead roles where reading group lists, monitoring status, and navigating contacts in the field is part of the operational role.

The HP71XEx's 1.47-inch display suits field operators and maintenance technicians where compact carry and one-handed operation are the priority.

Both models include a dedicated emergency button and Man Down alarm with location reporting. The emergency button triggers an emergency call that can pre-empt routine traffic on a trunking system, alerting the dispatcher with the activating terminal's ID and, where GNSS is configured, the device's location. Man Down alarm activates automatically when the device detects a fall or a period of inactivity beyond a configured threshold, transmitting an alert with the same location data.

Key confirmed specifications for HP71XEx IIC and HP79XEx IIC:

• IECEx and ATEX IIC, Zone 1 and Zone 2 (gas), Zone 21 and Zone 22 (dust)
• Individual call, group call, and emergency call on DMR digital channels
• 2W speaker, AI noise reduction, AGC
• Man Down alarm with location reporting
• Operating temperature -25°C to +60°C in classified areas
• BT 5.3, WLAN, and NFC for third-party application expansion and device management

TETRA Path: PT890Ex

For organisations operating TETRA trunking networks, the PT890Ex is Hytera's flagship intrinsically safe TETRA terminal. Individual calling, group calling, and emergency voice calling are defined capabilities within the TETRA standard, and the PT890Ex implements them within an ATEX marking of II 2G Ex ib IIC T4 Gb and II 2D Ex ib IIIC T90°C Db.

TETRA's emergency call handling differs from DMR in one important respect. The TETRA standard defines a dedicated emergency call service that automatically pre-empts routine calls, seizes a traffic channel, and delivers the alert to the dispatcher with priority. This behaviour is part of the protocol specification rather than a system-level configuration option, which means it applies consistently across the network without requiring per-terminal or per-site customisation.

TETRA Direct Mode Operation (DMO) extends individual and group calling capability to environments where the TETRA network signal is unavailable. A firefighter descending into a basement, a maintenance technician in a confined process vessel, or a responder in a signal-blocked underground area can maintain peer-to-peer communication with nearby team members in DMO without any base station involvement.

The PT890Ex also includes howling suppression and a water-porting speaker design. Howling suppression eliminates acoustic feedback when radios are in close proximity, relevant in confined process areas. The water-porting design maintains audio clarity after exposure to water jets or hosing-down events during maintenance shutdowns. Battery life reaches up to 26 hours in trunking mode (TMO) and 20 hours in direct mode (DMO) under a 5-5-90 duty cycle.

Choosing Between DMR and TETRA for a Hazardous-Area Deployment

The choice between DMR IS terminals and TETRA IS terminals follows from the existing network, not from a feature comparison.

If the organisation already operates a Hytera DMR Tier II or Tier III network, the HP71XEx and HP79XEx integrate into that infrastructure without requiring a separate network layer. If the organisation operates a TETRA network, or if the deployment requires the specific TETRA characteristics of standardised direct mode operation, guaranteed emergency call pre-emption at the protocol level, and interoperability with public safety TETRA systems, the PT890Ex is the applicable terminal.

For sites where both technologies are present, a gateway or convergence platform is required to bridge DMR and TETRA calls at the dispatch level. Confirm the interoperability configuration with Hytera during system design.

Frequently Asked Questions About Hazardous-Area Radios and Call Types

Does the emergency call on DMR IS terminals require a separate infrastructure configuration?

On a DMR Tier III trunking system, emergency call pre-emption and priority channel allocation are configured at the system level rather than per-terminal. The terminal sends an emergency call request to the trunking controller, which allocates a traffic channel and notifies the dispatch console.

The specific priority level and pre-emption behaviour depend on the system configuration during deployment. On a conventional DMR system, the emergency call activates an alert but does not include automatic channel pre-emption. Confirm the emergency call behaviour for the target system architecture with the Hytera team.

Can HP71XEx and HP79XEx terminals be used in the same talk group on the same DMR system?

Yes. Both models are standard DMR terminals and operate on the same channel and talk group plan without any compatibility issue. The HP79XEx and HP71XEx can be assigned to the same group, allowing supervisors carrying HP79XEx devices and field operators carrying HP71XEx devices to communicate within the same group call, make individual calls to each other, and trigger or receive emergency calls through the same system.

Do the IS terminals support all-call or broadcast call in addition to individual and group call?

On DMR trunking systems, broadcast call is available as an additional call type alongside individual, group, and emergency calls. On conventional DMR systems, all-call operates as a call to all radios on the active channel. Availability and configuration of broadcast and all-call depend on the system type and the specific codeplug programming. Confirm broadcast call availability and configuration with the Hytera team for the target deployment.

Confirm the Call Architecture Before the Terminal

Individual call, group call, and emergency call are supported on the HP71XEx, HP79XEx, and PT890Ex as standard capabilities of their respective radio standards. The more important planning question is how each call type behaves within the specific system infrastructure being deployed: whether emergency calls trigger pre-emption, whether individual calls are routed through the trunking controller, and whether DMO individual and group calls are available without network coverage.

Those questions belong in the system design phase, before terminal selection is finalised. Visit the Hytera Intrinsically Safe Radios range or contact a Hytera specialist to confirm the call architecture for your specific hazardous-area deployment.