Industry
Renan Meira
06/10/2026
Traditional copper telephone lines are gone in most markets. AT&T, Verizon, and Lumen have discontinued POTS infrastructure across large portions of the country, and the FCC’s 2022 forbearance order removed the requirement for carriers to maintain legacy copper infrastructure under its copper retirement rules, accelerating the discontinuation of POTS lines across most markets For fire alarm systems that still rely on a Digital Alarm Communicator Transmitter connected to an analog phone line, that means one thing: a POTS fire alarm communicator replacement is required to meet NFPA 72 requirements
Traditional copper telephone lines have been discontinued across most markets. AT&T, Verizon, and Lumen have phased out POTS infrastructure nationwide, and the FCC’s 2022 forbearance order removed the requirement for carriers to maintain legacy copper under its copper retirement rules, accelerating that transition.
For fire alarm systems that still rely on a Digital Alarm Communicator Transmitter connected to an analog phone line, that means one thing: the communication path no longer meets NFPA 72 requirements.
This is not a pending issue. It is happening now, and the systems affected are sitting at facilities where contractors and engineers will be held responsible when the AHJ shows up. Understanding what the code requires, what the listed replacement options are, and how to verify compliance before an inspection is what this post covers.
A Digital Alarm Communicator Transmitter is the device that sends fire alarm signals from the control panel to a supervising station. For roughly four decades, DACTs did this over analog copper telephone lines, which is what they were designed for. The name is somewhat misleading: the only thing digital about a DACT is that it dials digits. The transmission itself depended on a loop-start analog telephone circuit, which is a technology the major carriers no longer install or maintain.
When a DACT connects to a VoIP line instead of a true analog circuit, the signal is compressed and decompressed during transmission. That process corrupts or drops data packets. NFPA 72 explicitly prohibits the use of VoIP equipment for transmitting commercial fire alarm signals for this reason. A system that appears to have a working phone line may actually be riding over VoIP infrastructure without the building owner or contractor knowing it.
The NFPA 72 technical committee began phasing out DACT requirements as far back as 2013, when the 2013 edition eliminated the use of two telephone lines and required one of the two paths to be a different technology. The 2022 edition went further, and the current 2025 edition now governs all new communicator installations under a performance-based framework that makes a POTS-only DACT installation effectively impossible to justify.
*NFPA 72 – Chapter 26**
VoIP equipment shall not be used to transmit commercial fire alarm signals (Section 26.6.3). The standard requires any alternative communication method to demonstrate performance equal to or greater than traditional telephone lines in terms of reliability and signal integrity.
Chapter 26 of NFPA 72 governs supervising station alarm systems, including the communication path from the protected premises to the central station. The requirements differ depending on whether the system uses a single communication path or dual paths.
For a single communication path, Section 26.6.3.3 requires the path to be supervised at intervals of no more than 60 minutes, and any failure must be annunciated at the supervising station within 60 minutes. For dual paths, each path is supervised every 6 hours, with no single point of failure permitted to take down both paths simultaneously.
Alarm signals must be received and displayed at the supervising station within 90 seconds of activation, per Section 26.6.3.8. The 2025 edition also added new requirements under Sections 26.6.11.3 and 26.6.11.4, requiring communicators to be compatible with the latency and jitter characteristics of the network they run on. If latency or jitter causes a communication failure, the system must generate a trouble signal at the panel.
Additionally, the 2025 edition mandates cybersecurity compliance under the newly enforceable Chapter 11. Internet-connected fire alarm communicators are classified as Security Level 3, the highest tier, requiring compliance with UL 2900, ANSI/ISA-62443, or the NIST Cybersecurity Framework. Annual review of access credentials and logs is required.
*NFPA 72 – Section 26.6.3.3**
Single communication path: supervised at intervals not exceeding 60 minutes. Failure annunciated at the supervising station within 60 minutes. Dual path: each path supervised every 6 hours. No single point of failure may disable both paths.
Once a POTS fire alarm communicator replacement is required, the next step is selecting a communication path that meets NFPA 72 performance and supervision requirements. NFPA 72 Chapter 26 does not mandate a specific replacement technology. Instead, it requires that the chosen method meets the standard’s performance, supervision, and listing criteria. The most common compliant options are cellular communicators, IP communicators, and dual-path combinations of the two. This shift effectively requires a POTS fire alarm communicator replacement for any system still relying on an analog phone line.
Cellular Communicators
Cellular communicators send a heartbeat signal to the supervising station’s network operations center. If communication is lost, a trouble signal is generated within the 60-minute window required by Section 26.6.3.3. These devices must be listed for the application under UL 864 as either a fire alarm control unit subassembly or a stand-alone accessory. An off-the-shelf cellular module is not sufficient. The device must carry the UL 864 listing, and the specific listing category determines how it is wired and tested.
Some cellular communicators use a dialer capture approach, attaching to the existing DACT and converting the analog signal to cellular transmission. When this method is used, the system transitions from DACT operation to performance-based signaling under NFPA 72. The supervision and check-in requirements change accordingly, and the installation must be tested to confirm the panel generates a trouble signal locally when transmission fails.
IP Communicators
IP communicators transmit over an Ethernet network connection. They are subject to the same UL 864 listing requirements as cellular communicators and must meet the latency and jitter compatibility requirements added in the 2025 NFPA 72 edition. Because IP service can be interrupted by power outages and network failures, IP-only paths are less common for sole-path applications. Secondary power requirements under Section 26.6.3.13.1 require 24 hours of standby power for all transmitters and shared equipment necessary for signal transmission.
Dual-Path Cellular and IP
A combination of cellular and IP paths is the most commonly specified replacement for legacy DACT installations. Each path is supervised independently every 6 hours. Because neither path shares infrastructure with the other, a single failure cannot take down both. This approach also provides the redundancy that the original two-telephone-line DACT requirement was intended to deliver, but with modern technology that the carriers are still actively maintaining.
Before the next annual inspection, contractors and facility managers responsible for systems with legacy communicators should confirm the following:
The POTS sunset is not a future problem for fire alarm contractors and engineers to prepare for. The infrastructure is already gone in most jurisdictions, and systems that have not been upgraded are operating with a communication path that cannot meet the supervision and signal integrity requirements of NFPA 72 Chapter 26.
Replacing a DACT is not complicated, but it does require using listed equipment, verifying supervision intervals, and confirming that the panel behaves correctly when transmission fails. A communicator that looks like it is working during normal operations may not generate the required trouble signals when the path goes down, and that is the failure that surfaces at inspection. For any system still operating on an analog phone line, a POTS fire alarm communicator replacement is no longer optional—it is required for compliance.
What to Do Next
Pull the communicator model number on your next service visit and verify its UL 864 listing before the annual inspection. If the system is still running on an analog phone line or an unlisted cellular module, prioritize the replacement. Confirm with the supervising station that test signals are being received at the correct interval for the path type in use.
Find UL 864 listed cellular and IP communicators at FireAlarm.com, organized by panel compatibility and communication path type.
