Two-way communication systems provide emergency voice communication between building occupants who may need evacuation assistance and personnel at a fire command center, central control point, supervising station, emergency services location, or other approved location.
These systems are commonly associated with Areas of Refuge, accessible elevator landings, occupant evacuation elevator lobbies, and other accessible means of egress provisions. They are especially important for occupants who cannot safely use stairs during a fire or other emergency.
This guide explains when two-way communication systems are required, where call stations are installed, how Area of Refuge requirements differ from elevator-landing requirements, and how the International Building Code (IBC), NFPA 72, NFPA 101, ICC A117.1, and UL 2525 work together.
What Is a Two-Way Communication System?
A two-way emergency communication system allows a person requesting assistance to communicate back and forth with personnel at an approved receiving location.
Unlike a typical fire alarm emergency voice/alarm communication system that primarily broadcasts instructions to building occupants, a two-way communication system provides communication in both directions.
A typical system can include:
- A master or central control station
- Remote two-way call stations
- Audible communication
- Visible communication/status indication
- Supervised communication pathways
- Primary and secondary power
- Automatic off-premises communication where required
Depending on the building and applicable code requirements, remote stations can be located at Areas of Refuge, elevator landings, occupant evacuation elevator lobbies, or other required emergency communication locations.
Two-Way Communication vs. One-Way Emergency Voice Communication
This distinction causes considerable confusion in the field.
Two-way communication allows the occupant and receiving personnel to communicate with each other.
One-way emergency communication generally broadcasts instructions or emergency information to occupants without providing the same occupant-to-operator conversation through that communication path.
A fire alarm emergency voice/alarm communication system, often called EVACS, is a common example of a system used to distribute emergency voice instructions.
Two-way emergency communication serves a different purpose: it allows an occupant who needs assistance to call for help and communicate with responding or supervising personnel.
Example of a Two-Way Communication System
The photograph below shows an example of a Space Age Electronics SHIELD 30 two-way emergency communication system.
What Codes Cover Two-Way Communication Systems?
Several codes and standards can affect the design of a two-way emergency communication system.
- International Building Code (IBC) establishes many of the conditions under which two-way communication is required as part of an accessible means of egress.
- NFPA 101, Life Safety Code contains requirements for Areas of Refuge and emergency communication where that code is adopted.
- NFPA 72, National Fire Alarm and Signaling Code contains installation and performance requirements for emergency communications systems.
- ICC A117.1 addresses accessibility requirements that can affect signage, characters, operable parts, and accessible features.
- UL 2525 is the product safety standard associated with two-way emergency communication systems for rescue assistance applications.
When Is Two-Way Communication Required at Elevator Landings?
Under the modern IBC framework, a two-way communication system is required at elevator landings serving accessible floors that are one or more stories above or below the level of exit discharge, unless an applicable exception permits otherwise.
This is an important distinction. The requirement does not mean that every elevator in every new building automatically requires a two-way call station at every floor.
The accessible means of egress provisions, floor configuration, elevator type, ramps, Areas of Refuge, and other code conditions must be evaluated.
For a deeper discussion specifically focused on elevator landings, see our Elevator Landing Two-Way Communication Systems Code Guide.
Are Two-Way Call Stations Required at Every Elevator?
No. The IBC provides specific exceptions to the elevator-landing two-way communication requirement.
Depending on the adopted code edition and building conditions, exceptions can address situations such as:
- Communication already provided within qualifying Areas of Refuge
- Floors provided with compliant ramps
- Certain service elevators that are not part of the required accessible means of egress or accessible route
- Freight elevators
- Private residence elevators
- Other conditions specifically recognized by the adopted code edition
Always review the complete section and the locally adopted code before eliminating a required call station.
What Is an Area of Refuge?
An Area of Refuge is a designated location intended to provide a safer place for occupants who may need assistance during an emergency evacuation.
Areas of Refuge are part of the accessible means of egress strategy. They can allow an occupant who cannot use the stairs to wait for assistance while maintaining emergency communication with trained personnel.
Where an Area of Refuge is required, the applicable building or life-safety code determines its construction, size, accessibility, signage, communication, and other requirements.
Area of Refuge vs. Elevator Landing Two-Way Communication
These terms are frequently used interchangeably in the field, but they should not automatically be treated as the same thing.
An Area of Refuge is a specific code-defined location associated with an accessible means of egress.
An elevator-landing two-way communication station can be required at an accessible elevator landing even when that landing is not itself being designated as an Area of Refuge.
This distinction matters during design because the designer must first determine why the communication station is required before applying the appropriate requirements.
Where Does the Two-Way Communication System Call?
The required remote communication stations communicate with an approved receiving point such as a fire command center or other approved central control location.
Where the receiving location is not constantly attended, the applicable building code can require automatic off-premises communication to an approved supervising station or emergency services location.
Does a Two-Way Communication System Need Audible and Visible Signals?
Modern IBC requirements include both audible and visible communication/status features for required two-way communication systems.
The remote station must provide occupants with meaningful indication that their request for assistance has been transmitted and that communication has been established as required by the applicable code and equipment listing.
Because accessibility is a major part of these systems, designers should not evaluate the voice function alone. Visual indications, instructions, signage, mounting location, operability, and accessibility all need to be considered together.
UL 2525 and Two-Way Emergency Communication Systems
UL 2525 is an important product standard for two-way emergency communication systems used for rescue assistance applications.
Modern building and life-safety requirements reference listed equipment complying with UL 2525 in conjunction with installation requirements from NFPA 72.
When selecting a two-way communication system, verify that the equipment is appropriately listed for its intended application rather than assuming that any intercom or telephone system can satisfy the emergency communication requirement.
Two-Way Communication Signage Requirements
Signage is an important part of an accessible emergency communication system.
Operating instructions and identification information must be provided where required so occupants can understand how to request assistance and communicate their location.
Accessibility requirements can also apply to visual characters, tactile characters, Braille, the International Symbol of Accessibility, illumination, and directional signage depending on the particular sign and application.
Area of Refuge Signage
Required Area of Refuge signage can include identification of the refuge location, accessible means of egress information, and other directional or instructional information required by the applicable building and accessibility provisions.
Emergency Instructions at an Area of Refuge
Instructions at an Area of Refuge should tell occupants how to use the area during an emergency and how to summon assistance using the two-way communication system.
Directional Signage for Accessible Means of Egress
Directional signage can be required to identify accessible means of egress and direct occupants toward Areas of Refuge or other accessible egress components.
Depending on the building configuration, signage requirements can affect:
- Elevator landings
- Areas of Refuge
- Exits serving accessible spaces
- Exterior areas for assisted rescue
- Routes leading to accessible means of egress
The applicable IBC provisions and ICC A117.1 should be reviewed for the specific signage and accessibility requirements.
Two-Way Communication System Mounting Height
There is no single universal mounting height that should be applied to every component of every two-way communication system.
This is an area where designers need to distinguish between:
- Operable parts of the call station
- Tactile characters
- Visual characters
- Instructional signage
- Required accessibility reach ranges
- Manufacturer mounting requirements
For accessible call stations, the required operable portions must be located within the applicable accessible reach ranges. Signage must independently comply with the requirements applicable to the type of sign being installed.
NFPA 72 and Two-Way Emergency Communication Systems
NFPA 72 addresses Emergency Communications Systems (ECS) in Chapter 24.
Two-way emergency communications addressed by NFPA 72 include applications such as:
- Area of Refuge emergency communication
- Elevator-landing communication
- Stairway communication
- Occupant evacuation elevator lobby communication
- Fire service communications
NFPA 72 provides requirements affecting equipment, pathways, supervision, power supplies, survivability, system operation, and testing.
The exact section numbering can change between NFPA 72 editions, so always verify the adopted edition rather than relying exclusively on a section number from an older design or specification.
Does the Two-Way Communication Wiring Need to Be Supervised?
Required emergency communication pathways must be monitored for integrity as required by NFPA 72 and the system design.
The purpose of pathway supervision is simple: a wiring failure that prevents an occupant from calling for assistance should not remain hidden until an emergency occurs.
The equipment listing, pathway class, system architecture, NFPA 72 requirements, and manufacturer's instructions all need to be considered when determining the required supervision.
Two-Way Communication System Battery Backup
Emergency communication systems require reliable primary and secondary power in accordance with the applicable NFPA 72 requirements and equipment listing.
Battery calculations should be based on the system's required standby and active operating periods, connected equipment load, manufacturer data, and the NFPA 72 edition adopted for the project.
Avoid assuming that an old standby/active-time rule automatically applies to every modern two-way communication system. The system type, equipment listing, adopted NFPA 72 edition, and applicable building-code requirements must be evaluated together.
Pathway Survivability for Area of Refuge and Elevator Communication
Pathway survivability is one of the most important technical considerations for wired emergency communication systems.
The goal is to prevent a fire in one portion of the building from unnecessarily disabling emergency communications needed by occupants in other protected locations.
Depending on the system configuration and applicable NFPA 72 requirements, pathway survivability can involve:
- Fire-resistive or circuit-integrity cable systems
- Listed electrical circuit protective systems
- Protected shafts, enclosures, or areas
- Building sprinkler protection
- Separation or routing of redundant pathways
- Other approved survivability methods
The required survivability level is not determined solely by whether a building is described as having two-hour construction. Modern NFPA 72 requirements evaluate the location and configuration of pathways, protected areas, communication stations, notification zones, and system architecture.
Building Construction and Fire-Resistance Ratings
Building construction and fire-resistance ratings can still be important when evaluating emergency communication pathways, but they must be considered as part of the complete code analysis.
Two-Hour Circuit Integrity Cable
Where a two-hour fire-resistive pathway is required, one possible method can involve a listed circuit-integrity or fire-resistive cable system installed in accordance with its listing.
Important: Installing cable marketed as "CI cable" does not by itself make an installation compliant. The complete listed system, installation method, supports, raceway or protection requirements, terminations, and other listing conditions must be followed.
Stairway Communication Systems
Two-way emergency communication requirements are not limited to Areas of Refuge and elevator landings.
Building codes can require communication within certain stairways, particularly in high-rise or other regulated applications. These systems provide communication between designated stairway locations and an approved constantly attended station or other approved receiving location.
Stairway communication should therefore be evaluated separately from Area of Refuge and elevator-landing communication when reviewing a project's emergency communication requirements.
Occupant Evacuation Elevator Communication
Buildings using occupant evacuation elevators have additional communication requirements associated with the elevator evacuation strategy.
Two-way communication can be required within occupant evacuation elevator lobbies so occupants can communicate with an approved emergency control location while waiting for or using the evacuation system.
For more information about these elevators, see our Occupant Evacuation Elevator Code Guide.
How Often Are Two-Way Communication Systems Tested?
Two-way emergency communication systems must be inspected and tested in accordance with the applicable NFPA 72 requirements, equipment listing, manufacturer's instructions, and requirements of the AHJ.
Testing should verify more than the physical presence of the call station. Depending on the system and applicable requirements, testing can include communication operation, visual and audible indications, pathway supervision, trouble conditions, power supplies, secondary power, and communication with the receiving location.
Always use the inspection and testing table from the NFPA 72 edition adopted for the project rather than carrying forward a table number or test frequency from an older edition without verification.
Two-Way Communication Design Checklist
- Determine which building and fire code editions are adopted.
- Identify the level or levels of exit discharge.
- Identify all accessible floors.
- Determine the required accessible means of egress from each floor.
- Identify required Areas of Refuge.
- Identify elevator landings requiring two-way communication.
- Check all applicable IBC exceptions.
- Determine whether occupant evacuation elevators are provided.
- Determine whether stairway communication is required.
- Identify the approved central control or fire command location.
- Determine whether that location is constantly attended.
- Determine whether automatic off-premises communication is required.
- Verify equipment listing, including UL 2525 where applicable.
- Verify NFPA 72 installation requirements.
- Verify accessible call-station operation and mounting.
- Provide required operating instructions and signage.
- Determine pathway supervision requirements.
- Determine pathway survivability requirements.
- Calculate secondary power requirements.
- Coordinate monitoring and off-premises communications.
- Verify inspection and testing requirements.
- Confirm the final design with the AHJ.
Frequently Asked Questions About Two-Way Communication Systems
Is a two-way communication system required at every elevator landing?
No. The requirement depends on whether the floor and elevator landing fall within the applicable accessible means of egress provisions and whether an IBC exception applies.
What floors require elevator-landing two-way communication?
Under the modern IBC framework, the requirement generally applies to elevator landings on accessible floors that are one or more stories above or below the level of exit discharge, subject to the applicable exceptions.
Is an elevator landing automatically an Area of Refuge?
No. An elevator landing and an Area of Refuge are related concepts within accessible means of egress design, but they are not automatically the same thing.
Does an Area of Refuge require two-way communication?
Where an Area of Refuge is required by the applicable code, two-way emergency communication is generally part of the Area of Refuge requirements, subject to the specific provisions and exceptions of the adopted code.
Where does an Area of Refuge call box communicate?
The communication system connects occupants to an approved central control point, fire command center, supervising station, emergency services location, or other location permitted by the applicable code and approved by the AHJ.
Does the two-way communication master station have to be constantly attended?
If the designated receiving location is not constantly attended, the applicable building code can require automatic off-premises communication to an approved supervising station or emergency services location.
Does a two-way communication system require UL 2525 equipment?
Modern code provisions reference UL 2525-listed two-way emergency communication equipment for applicable rescue-assistance systems. Verify the adopted code edition and the listing of the proposed equipment.
Does two-way communication wiring require two-hour CI cable?
Not automatically. Pathway survivability requirements depend on the applicable NFPA 72 provisions, system architecture, pathway location, building protection, and other conditions. A two-hour fire-resistive pathway is one possible requirement or solution in certain applications.
Does a two-way communication system need battery backup?
Emergency communication systems require secondary power in accordance with the applicable NFPA 72 requirements and equipment listing. Required capacity must be calculated for the specific system.
Who determines whether a two-way communication system is required?
The requirement is established by the adopted building, fire, life-safety, and accessibility codes and ultimately interpreted and enforced by the Authority Having Jurisdiction.
California Author's Note
California projects should also be reviewed against the currently adopted California Building Code and California Fire Code, including California amendments and accessibility provisions.
The fundamental design process remains the same: determine the accessible means of egress, identify required Areas of Refuge and elevator-landing communication locations, apply the applicable exceptions, then coordinate the emergency communication system with the adopted NFPA 72 requirements.
Because California accessibility and building-code provisions can modify or supplement the model-code requirements, designers should verify the currently adopted California code cycle and local amendments before finalizing a project.
Related FireAlarmsOnline Guides
If you are designing or troubleshooting emergency communication and elevator fire alarm systems, these related guides may help:
- Elevator Landing Two-Way Communication Systems
- Occupant Evacuation Elevator Code Requirements
- Elevator Shunt Trip Requirements & Codes
- 520 Hz Fire Alarm Requirements
- Fire Alarm Codes vs. Standards
Final Thoughts
Two-way emergency communication systems are an increasingly important part of accessible building evacuation design. The key is understanding that Area of Refuge communication, elevator-landing communication, stairway communication, and occupant evacuation elevator communication are related but distinct applications.
Start with the adopted building or life-safety code to determine where and when communication is required. Then use NFPA 72, the equipment listing, accessibility requirements, manufacturer instructions, and AHJ requirements to determine how the system must be designed, installed, supervised, powered, and tested.
That approach produces a much cleaner design than beginning with a call-box layout and trying to reverse-engineer the code requirements afterward.
