Tuck · Offline baby monitor
A baby monitor that works without Wi-Fi
TL;DR. Tuck has a custom Bluetooth Coded PHY (S=2) transport that connects two paired iPhones directly — no Wi-Fi, no cellular, no router. Built for hotels with broken networks, cabins off the grid, flights, and any home where the nursery is the one room Wi-Fi doesn't reach.
Where regular baby monitors fail
Almost every modern baby monitor — phone-based or hardware — depends on Wi-Fi for video and audio. That's fine until you travel. Most parents who try a Wi-Fi baby monitor on their first family vacation discover the same thing: the hotel's Wi-Fi can't carry continuous video, the cellular signal in the hotel room is weak, and the cabin they rented is intentionally off-grid.
The "solution" most apps offer is to spin up the parent phone as a Wi-Fi hotspot for the nursery phone. It works, kind of, until the parent phone goes to sleep, drops the hotspot, and you wake up with a half-dead battery and no monitor. Or until you board a plane.
Tuck's offline transport is engineered for these moments — it's the reason Bluetooth Coded PHY is in the product at all.
How offline mode works
Pair your two iPhones once on Wi-Fi
Initial pairing happens once, over your home Wi-Fi or cellular, via QR code. After that, the two phones know each other and can talk over Bluetooth without ever touching the internet again.
Switch the nursery iPhone to airplane mode
When you travel, put the nursery iPhone in airplane mode and re-enable Bluetooth. Tuck automatically detects the loss of Wi-Fi/cellular and switches to its Bluetooth Coded PHY transport.
Watch and listen, no internet required
From the parent device, the live audio feed is uninterrupted. Video drops to a low-rate slideshow (about one frame every 2 seconds) so it can fit through Bluetooth's bandwidth budget. Cry alerts and two-way talk continue working.
Auto-rejoin Wi-Fi when you're back home
When the nursery iPhone reconnects to Wi-Fi or cellular, Tuck automatically upgrades back to full HD video over LiveKit. You don't need to flip a setting — the transport tier picker runs continuously in the background.
Range — what to expect in practice
Bluetooth Coded PHY's S=2 mode trades raw bandwidth for range. Some rough numbers from our testing:
- Hotel suite (parent in living room, baby in bedroom): solid link, no audio dropouts. Most suites are well within 15 meters of partition.
- Apartment (single-floor, two bedrooms): solid link even with two interior walls between. Concrete walls reduce range more than drywall.
- Two-story house (parent on main floor, baby in upstairs nursery): typically works with 1–2 occasional brief audio artifacts. If your house is large, this is the case where Wi-Fi remains the better tier.
- Cabin or AirBnB: works as long as the building is roughly apartment-sized; struggles in sprawling layouts. Solid for the typical 2-bedroom rental.
- Plane: works easily — parent in seat, baby sleeping in bassinet a few rows back. Bluetooth ranges remain comfortably within plane geometry.
When the link does drop, Tuck holds the audio buffer for a couple of seconds and reconnects automatically — you'll usually hear a brief pause rather than a notification.
Frequently asked questions
Does Tuck really work without Wi-Fi?
Yes. Tuck's Bluetooth Coded PHY transport is a peer-to-peer link between the two iPhones — no router, no internet, no cellular required. Audio passes natively, video is delivered as a low-rate slideshow (about 1 frame / 2 seconds), cry alerts and two-way talk both work.
What's BLE Coded PHY?
Bluetooth Coded PHY is a long-range, low-data-rate physical layer in Bluetooth LE. Standard Bluetooth runs at 1 Mbps with about 30 meters of line-of-sight range. Coded PHY (the S=2 variant Tuck uses) runs at 500 kbps with about 60 meters line-of-sight, or 30–50 meters indoors through walls. It's the same technology Apple uses for AirTag Find My ranging.
What iPhones support Coded PHY?
iPhone 11 and later. Tuck requires iOS 17 or later, which means iPhone XS/XR or newer — every supported iPhone has Coded PHY available.
How far can the two iPhones be apart?
30–50 meters indoors through typical drywall walls; up to 60 meters line-of-sight (e.g., across a hotel suite or a cabin loft). That covers most apartments, most one-floor houses, hotel rooms, and the main cabin of a larger boat. For a very large multi-story house, Wi-Fi remains the better transport.
Will the offline link work on a plane?
Yes. Bluetooth is allowed on planes — it's part of FAA-approved 'airplane mode' wireless. Tuck's Bluetooth Coded PHY doesn't transmit on cellular bands at all, so it stays compliant with airplane rules. We've tested this on real flights as part of validation.
What about a hotel with no Wi-Fi (or broken hotel Wi-Fi)?
This is the canonical use case Tuck was built for. Most hotel Wi-Fi is unreliable, captive-portal-gated, or simply absent. Bluetooth Coded PHY works regardless — the two iPhones talk directly without involving the hotel's network at all.
What if the nursery iPhone is on Wi-Fi but the parent isn't?
Tuck's transport tier negotiation handles this case automatically. The system picks the best mutual transport — if both phones can reach each other over the internet (one via Wi-Fi, one via cellular), Tuck uses LiveKit WebRTC. If only Bluetooth is available end-to-end, Tuck uses Coded PHY. There's no setting to fiddle with; the cutover is seamless.
Is video quality bad on Bluetooth?
Compared to Wi-Fi: yes. Bluetooth Coded PHY can carry roughly 50 KB/s of usable application data, which is enough for continuous compressed audio and a low-rate video slideshow (≈1 frame every 2 seconds, ≈160×120 thumbnail). It's enough to confirm baby's position and breathing pattern visually; it's not full HD video. We've found in user testing that audio matters more than video at night, so we prioritize audio bandwidth.
Is the offline link encrypted?
Yes. The Bluetooth Coded PHY link uses Bluetooth LE Secure Connections (the standard ECDH-based encryption baked into BLE) plus an additional application-layer key derived during initial QR pairing. The two iPhones must have paired beforehand for the link to work — a stranger can't connect to your nursery phone over Bluetooth.
What about battery drain on the nursery iPhone?
We recommend keeping the nursery iPhone plugged in. With the screen in dim ambient mode, Coded PHY active, and audio capture running, we measure roughly 4–6% battery per hour — too high for unplugged overnight monitoring on most older iPhones. Plug it in.
Why don't more baby monitors do this?
Two reasons. First, Coded PHY is a relatively new Bluetooth feature (5.0+, mainstream iPhone support since 11). Second, doing it well requires custom protocol work — Apple's Bluetooth APIs don't expose Coded PHY directly, so we built a custom transport stack. Most baby-monitor apps stop at "Bluetooth" meaning the standard 1M PHY at 30m, which isn't reliable enough through walls. We invested in the long-range version because it's the difference between "works in a hotel suite" and "loses signal between bedroom and bathroom."
Try Tuck
Offline monitoring is included in the Tuck Free tier. You don't need to subscribe to use Tuck without Wi-Fi.