# Emergency two-way communication system

> An emergency two-way communication system is a code-required system that lets a person in a specific location — an elevator cab, an area of refuge, an elevator landing — talk with a staffed point that can summon help, without needing to dial or carry a phone.

- Also known as: two-way emergency communication, emergency communication system, two-way communication system
- Last reviewed: July 30, 2026

## How it works

Different codes require these systems in different places: ASME A17.1/CSA B44 requires two-way communication from elevator cabs; the IBC requires it in areas of refuge and at certain elevator landings used for accessible egress. Newer elevator code editions add requirements serving people who cannot speak or hear — such as messaging/display capability and video monitoring — so responders can communicate regardless of ability. The stations connect to a constantly attended point, over supervised communication paths.

## Why it matters

These systems' communication paths were classically analog copper lines, and they carry the strictest expectations of any endpoint in a POTS migration: automatic connection, supervision, battery-backed operation, and acceptance by the authority having jurisdiction. They should be identified explicitly in any copper-retirement inventory.

## Common use cases

- Elevator cab emergency phones reaching a monitoring service
- Area-of-refuge call stations connecting to a fire command center
- Elevator-landing two-way communication for accessible egress

The migration rule of thumb: anything a trapped or immobilized person depends on to reach
help gets engineered and inspected first, not last.

## What these systems have to survive

The engineering requirement behind every one of these systems is the same: they have to work at
the moment the building is at its worst. That constrains the design in ways an ordinary voice
circuit is not constrained.

Power is the first constraint. The system must remain functional after the building loses
power, for a duration the applicable code and the AHJ establish — which means backup power
sized and verified, not assumed.

Detectability is the second. A system that fails silently between inspections is worse than a
system known to be down, because it produces false confidence. The path needs supervision that
raises a trouble condition when it breaks.

Answerability is the third and most frequently overlooked. Two-way means someone answers. When
a migration changes the path, confirm that the far end still rings through to a location that
is actually attended, and test it by speaking to the person who answers.

Verify all three at acceptance and record the results. Each is separately inspectable.

## Common misconceptions

**Claim:** A cell phone in your pocket satisfies the requirement.

**Correction:** The codes require built-in systems available to anyone at the location, connected to an attended point, functioning during power loss — personal phones satisfy none of that.

## Frequently asked questions

**What changed in recent elevator code editions?**

Editions of ASME A17.1/CSA B44 from 2019 onward added two-way messaging/display and video requirements so occupants who cannot speak or hear can still communicate with responders. Which edition applies to a given building depends on the jurisdiction's adoption.

## Sources

- [2024 International Building Code](https://codes.iccsafe.org/content/IBC2024P1) — International Code Council
- [ASME A17.1-2025/CSA B44 Safety Code for Elevators and Escalators](https://blog.ansi.org/ansi/asme-a17-1-2025-safety-code-elevator-csa-b44/) — ANSI (blog summary of the ASME/CSA code)


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Canonical page: https://dataremote.com/newsroom/definitions/emergency-two-way-communication-system
Organization: DataRemote, Inc. — POTS line replacement, cellular failover, and fixed wireless access solutions. https://dataremote.com