How to Turn an Old iPhone Into a Baby Monitor

If you’ve got an old iPhone sitting in a drawer, you’re sitting on a perfectly good baby monitor. Whether you’re traveling, visiting family, need a backup, or just want a simple audio monitor without buying more hardware — two iPhones and an app are all you need.

Here’s how to do it with EarHorn.

What you need

• An old iPhone running iOS 16.7 or later (iPhone 8 and newer all work)
• Your current iPhone as the parent device
• A charging cable for the old phone — you’ll want it plugged in
• Both devices on the same WiFi network

That’s it. No extra hardware, no account to create, no subscription.

Why an old iPhone works well as a baby monitor

A phone you’re not using anymore is ideal for this:

• It can stay plugged in permanently — no battery anxiety
• It doesn’t need cellular service — WiFi is all EarHorn needs
• The microphone is good — even older iPhones have quality mics
• You’re not giving up a device you use daily

Most families have at least one old iPhone in a drawer after upgrading. Before you trade it in for $50, consider that it might be worth more as a baby monitor.

Step-by-step setup

1. Update the old iPhone

Make sure it’s running iOS 16.7 or later. Go to Settings > General > Software Update. Even an iPhone 8 supports iOS 16.

2. Connect it to your home WiFi

The old phone doesn’t need a SIM card or cellular plan. Just connect it to the same WiFi network your current phone uses.

3. Download EarHorn on both devices

Install EarHorn from the App Store on both the old iPhone and your current phone.

4. Set up roles

• On the old iPhone: choose Baby
• On your current phone: choose Parent

5. Pair with the code

The baby device will show a 6-character pairing code. Enter it on the parent device. This creates a secure, encrypted connection between the two phones.

Once paired, the devices will reconnect automatically in the future — you won’t need the code again.

6. Place and plug in

Put the old iPhone in the nursery, plugged into a charger, close enough to pick up sound but out of the baby’s reach. A gooseneck phone mount (the flexible clamp-arm holders that attach to a nightstand or furniture) works well for positioning. Important: Keep the phone and all cables out of the baby’s reach. Never place cords within reach of the crib. Ensure any mount is securely attached and cannot fall into the crib. Follow CPSC and AAP safe sleep guidelines. EarHorn will start listening and will stream audio to your phone when it detects sound above your set threshold.

Tips for the best experience

Adjust the threshold. Every room is different. If you’re getting too many alerts, raise the threshold from the parent device. If you’re not getting alerts when the baby cries, lower it. You can adjust remotely — no need to go back into the nursery.

Keep the baby device plugged in for extended monitoring. The baby device uses the microphone continuously, so it draws more power than idle. EarHorn will alert you at 20% and 10% battery, but a charging cable means you don’t have to think about it.

Use Do Not Disturb on the baby device. You don’t want notification sounds from other apps waking the baby. Turn on Do Not Disturb or Focus mode on the old iPhone.

Position matters. Place the phone close enough to pick up sound, with the microphone (bottom of the phone) facing toward the baby. Keep the phone, mount, and all cables out of the baby’s reach. Avoid placing it near fans or white noise machines if possible.

When is a phone monitor the right call?

Hardware baby monitors are great for a dedicated nursery setup at home. But there are plenty of situations where they’re not an option:

• Traveling: Hotels, Airbnbs, vacation rentals — your nursery camera stays at home (tip: some hotel WiFi networks block device-to-device communication; a small travel router solves this)
• Visiting family: Grandparents’ house, friends with a guest room, holiday gatherings
• Backup: When your main monitor breaks, runs out of battery, or you just need a second option
• Simplicity: Sometimes you just need audio monitoring without buying and mounting more hardware

EarHorn fills that gap. It uses the hardware you already have, sets up in under a minute, and works anywhere you have WiFi and two phones. It’s the monitor that’s always in your pocket.

What about security?

EarHorn uses P-256 elliptic curve cryptography, a widely-used industry standard, to authenticate devices and encrypt the connection. Audio data streams peer-to-peer over your home WiFi and doesn’t pass through any external servers. There are no cloud servers to breach, no accounts to hack, and no video footage stored anywhere.

The 6-character pairing code uses PBKDF2 key derivation with 600,000 iterations, and failed pairing attempts trigger exponential backoff lockouts. Protecting your home WiFi network is what protects your monitor — and EarHorn adds strong encryption on top of that.

Get started

EarHorn will be available on the App Store in April 2026. That old iPhone isn’t going anywhere — it’ll be ready when you are.

EarHorn is a convenience tool for audio monitoring and is not a substitute for attentive supervision.