A baby monitor away from home

Bedtime is at seven wherever you are. Away from home the monitor you trust is usually in a cupboard three hundred miles behind you — and on the trips where you did remember to pack it, a hotel corridor eats the signal by the third fire door.

There are three answers to that, and two of them have nothing to do with us.

Does your own baby monitor travel well?

The boring answer is often the right one. A dedicated pair on its own frequency — DECT, or one of the 2.4 GHz units — needs no network at all, which is exactly what you want in a rented flat with a router you cannot log into.

What tends to go wrong:

• Two units, two chargers, and a parent unit the size of a paperback. It is the first thing dropped from the bag when the bag has to close.
• Range figures are measured outdoors with nothing in the way. Hotel walls are not nothing, and a corridor with fire doors is far worse than the same distance at home.
• Wi-Fi cameras need the network. Guest networks that keep clients from seeing each other — most hotels, plenty of holiday lets, most campsites — will simply not let the camera and your phone find one another. And re-pairing a camera to a new network is a job for daylight, not for a dark room with a baby in it.
• Abroad, there is the plug adapter you did remember, and, on some units, a radio band that is allocated differently outside the region they were sold in. Worth a look before you rely on it.

Is a travel baby monitor worth buying?

Audio-only DECT units are cheap and pack down to almost nothing, and they work where there is no network at all. The cost is a second device to own, charge and remember for maybe six nights a year. Easy to justify if you are away every month; hard for one summer holiday.

Can you use the phones you already carry?

Two phones, or a phone and a laptop, or an old tablet that lives in a drawer. They are already in the bag, already charged, and every one of them has a microphone. Five things worth checking before you trust one for a whole evening:

• Does it alert you with the phone locked and the page closed? A lot of browser monitors only make a noise inside their own open tab, which means leaving a phone unlocked, screen lit, page in front of you. No good at dinner, and no good for the battery.
• Does it tell you when the link drops? A monitor that has gone quiet because the Wi-Fi died looks exactly like a monitor that is quiet because the baby is asleep. That is the failure that actually matters, and it is the one most tools say nothing about.
• Do both ends have to match? An iPhone by the cot and an Android in your pocket is an ordinary household, and a surprising number of apps cannot do it.
• Does it want an account and a card before it will work once? Half past seven in an unfamiliar flat is a bad moment to find that out.
• Does it need both devices on the same Wi-Fi? If it does, you cannot leave the building, which is usually the whole point.

A longer look at which device belongs at which end is in using your phone as a baby monitor.

What works where: hotels, rentals, grandparents, campsites

A baby monitor for a hotel room

The awkward part is that you are usually not in another room. You are in the corridor, downstairs at dinner, or out on the terrace: a short distance through a great many walls, on a network that may refuse to let two of your own devices talk. Anything that connects the two devices over the internet rather than over the local network is untroubled by that. Whatever you use, plug the device by the cot into power — it is going to sit there for three hours.

A holiday rental or an Airbnb

Thicker walls than you are used to, a layout you learned this afternoon, and a garden you would quite like to sit in. Test it on the first evening while the baby is still awake, rather than discovering the dead spot at nine o'clock.

At the grandparents' house

The house where you almost never have the monitor with you, and the one where there is always a drawer with an old phone in it. Often the nursery is two floors from the kitchen, which is further than it sounds.

Camping, a van, a boat

No Wi-Fi at all, so the question is whether the thing works over mobile data. A DECT unit needs no network whatsoever and is genuinely hard to beat here, as long as you can charge it. Anything running over the internet needs a signal, and sound alone costs a small fraction of what video costs when the signal is thin.

Before the first night

• Test it at home, in the configuration you are actually going to use.
• Put the device by the cot on a charger.
• Silence the other notifications on the phone you keep, not the monitor's.
• Leave video off unless you want it; sound uses a fraction of the data.
• Agree who is listening. Two adults each assuming the other one has an ear on it is the oldest failure of the lot, and no device fixes it.

Where NapLink comes in

We built it for this gap: the nights when the monitor you own is at home, or is in the building and still not reaching you. It is a web page, so there is nothing to install and no account to make. You open it on the device that stays with the baby, scan the code with the one you keep, and it is listening.

The two devices connect to each other over the internet, so a hotel guest network or a phone on mobile data is fine, and they do not have to match: an iPhone by the cot and an Android in your pocket works, either way round. The alert reaches a locked phone with the page closed. And when the link drops, both ends say so — a quiet screen here never means two things at once. It is free.

NapLink is not a medical or safety device. It depends on two devices, their batteries, their browsers and a network, any of which can fail without warning. Never rely on it as your only means of supervising a child.