Cheapest route to phone alerts

Smoke & CO Alarm Listener

Ring Canada & United States $ · Works with the alarms you already own

A small device that sits beside an existing smoke or CO alarm and listens for its alarm pattern, then pushes an alert to your phone. It does not detect anything itself — it hears the alarm you already have.

Why we like it

A fraction of the cost of replacing alarms with smart ones
Works over Amazon Sidewalk, so it functions without your Wi-Fi or power
Optional professional monitoring on a subscription

Watch out for

Detects nothing itself — it is entirely dependent on the alarm beside it
Must sit within 6 inches of the alarm, and the alarm must be under ten years old

Best for

Getting phone alerts from a houseful of existing alarms without replacing any of them.

Read the full market guide — costs, install effort and alternatives ↓

Market guide

The whole commitment, end to end

What this actually is, what the market looks like, what it really costs, and how much of your time it wants — before you spend anything.

Buying it Trivial

Installing it Trivial

Living with it Easy

Up front

CAD $50-$70 per listener, one per alarm you want covered.

Lead time

Days

Time to install

15 minutes including app setup

How it works

Since 1996, North American fire alarms have been required to sound a standard three-pulse temporal pattern for fire, and CO alarms use a distinct four-pulse pattern. Those patterns are machine-recognisable, which is what makes a listener possible: a microphone, a pattern matcher and a radio. It hears your alarm, identifies which hazard, and sends the alert.

What the market looks like

A small category with essentially one mainstream product, Ring's Smoke & CO Listener at around CAD $55, plus a handful of similar devices from smaller brands. The concept is sound and the price is compelling against replacing five alarms with smart ones at CAD $170 each. What is missing is independent testing: we found reviews but no controlled study of false-negative or false-positive rates, which for a life-safety accessory is a real gap.

Features that actually matter

Pattern recognition: Distinguishes the fire pattern from the CO pattern and tells you which, because the correct response differs.
Works without Wi-Fi: Amazon Sidewalk gives it a low-bandwidth path out of the house independent of your router — a genuine resilience advantage over Wi-Fi-only smart alarms.
Optional professional monitoring: Adding a subscription turns it from a notification device into a monitored one, which is the cheapest route to dispatch we found.
Placement constraint: Within 6 inches of the alarm. This is a hard requirement and easy to violate the next time someone paints a ceiling.
Age constraint: The manufacturer requires the existing alarm be ten years old or less — which is the rule you should be following anyway.

What it really costs

Up front: CAD $50-$70 per listener, one per alarm you want covered.
Consumables: Batteries per the model.
What else you'll need: Optional monitoring subscription.
Over five years: Purchase price plus any subscription.

Figures are typical street prices in Canadian and US dollars as of September 2026, gathered from public retail listings. They move with the season and with the exchange rate — treat them as a planning band, not a quote.

How it differs from the alternatives

Versus replacing alarms with smart ones: Roughly a third of the cost, and you keep working alarms rather than binning them. The trade is an extra component in the chain.
The derivative-device problem: A listener adds a second point of failure on top of the alarm: microphone, placement, battery, radio link. If the parent alarm fails, the listener reports nothing, because there is nothing to hear.
The honest gap: We could not find independent reliability testing of listeners. The mechanism is sound and the standardised alarm patterns make it tractable, but nobody has published false-negative rates. Treat it as a useful supplement rather than as protection you would bet the house on.

Buying it

Effort Trivial

Where: Amazon, Ring direct, big-box electronics.

Lead time: Days

Check it is supported in your country and at your address — professional monitoring is unavailable at commercially-zoned addresses.

Installing it

Effort Trivial

Time: 15 minutes including app setup

You'll need: Phone · Ladder

Mount within 6 inches of the alarm and then actually test it: press the alarm's test button and confirm the notification arrives. Do that again after any painting, alarm replacement or router change.

Living with it

Effort Easy

Retest the full chain a couple of times a year, and re-check the 6-inch placement after any ceiling work. Remember the listener's clock is tied to the alarm's: when the alarm hits ten years, replace it or the listener has nothing valid to listen to.

If not this, then what

Smart smoke and CO alarmsFewer failure points, three times the price, and you replace working alarms.
Professional monitoringThe only option that dispatches the fire department without you.

Our verdict

The best value in this category if you already have decent alarms — but understand you are buying a microphone with a radio, not a detector. Test the whole chain when you install it, and again whenever anything in the house changes.

We don't take payment for placement and we don't sell these products. If you think we've got something wrong here, tell us — we'll correct it.

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