MurmeliA baby monitor app without Wi-Fi: what works and what doesn't
A baby monitor app works without an internet connection as long as both phones are on the same network. While you are out, it works over mobile data. With no network at all, meaning neither Wi-Fi nor mobile coverage, it does not work. Which of these situations applies to you determines the answer.
This guide comes from the team behind the baby monitor app Murmeli. It describes what applies to apps of this kind in general, and it also names what none of them can do.
What does "without Wi-Fi" actually mean?
The same search covers three situations with different answers.
In the first, you have a router and a Wi-Fi network at home, but no internet at the moment. The line is down, or you are in a holiday home with a router and no contract.
In the second, you are not at home. The child is asleep in the flat while you sit in the garden or next door, and your phone is on mobile data.
In the third, there is no network at all, neither router nor mobile coverage. That happens in a mountain hut or on a campsite without reception.
Does a baby monitor work without internet but with Wi-Fi?
It does, as long as both phones are on the same router. The devices then talk to each other directly, and the data goes from one to the other without passing through a server. Whether the router behind them is connected to the internet makes no difference. A router without a contract still provides a local network.
Two router settings can prevent this, and both are quick to check.
Guest network. Many routers separate guest devices from the rest. A phone on the guest network cannot reach another one on the main network. Both devices have to be on the same network; being on the same router is not enough.
Client isolation. Some routers, particularly in holiday flats and hotels, forbid devices on the Wi-Fi from seeing each other at all. As a guest you usually cannot change this setting. When pairing fails in such a place, this is almost always why.
Murmeli looks for this direct route on its own and takes it when it is open. When it is blocked, the app falls back to the detour.
A baby monitor over mobile data while you are out
That works too, and for many people it is the actual reason to choose an app instead of a dedicated device.
What matters here is what "out" means for each device. The phone with the child normally stays at home on Wi-Fi and on the charger. Only your parent device moves to the mobile network. Each of the two devices needs a connection, but it does not have to be the same one.
Because the devices are now on different networks, they can no longer find each other directly. A relay server connects them. Many apps do not say where that server stands. If that matters to you, clarify it before you buy, because you cannot tell from the app afterwards.
Data usage depends mainly on the video. A night with the picture running over mobile data is noticeable on your allowance. If you leave the sound running and switch the picture on only when you need it, very little is used.
What uses more, sound or picture?
The video uses more, both in data and in battery. The camera is the component with the highest power draw, and video data needs a multiple of what speech and noises require. This is why many apps start with the picture switched off and let you turn it on.
For a whole night this means sound throughout, picture only when you hear something. The phone with the child belongs on the charger anyway, otherwise the battery is empty before morning. An old device with a tired battery can serve as the baby device as long as it stays on power.
What does not work: no network at all
Two phones cannot set up an audio link across a distance without Wi-Fi and without mobile coverage. Bluetooth does not reach far enough and is not intended for continuous audio between two phones. A hotspot on one of the two devices does create a network and therefore behaves like the first case, but it drains the battery of the device that has to last the night.
A classic baby monitor with its own radio link builds its own network and needs neither a router nor mobile coverage. If you regularly stay in places without reception, such a device is the better choice.
What to watch out for when there is no Wi-Fi
A few things make the difference when the connection is not the usual one.
Power. The baby device belongs on the charger every night. Without a stable network a phone searches more, and that costs battery.
Calls. An incoming call interrupts the audio link on both platforms. On the device with the child it helps to switch on flight mode and then turn Wi-Fi back on. The Wi-Fi connection stays up while calls no longer come through.
Volume. Turn both phones up. A setting that is too quiet is a common reason for a missed alert.
Test unfamiliar networks first. In a holiday flat, do not assume it will work in the evening. Pair once while the child is still awake.
Supervision. A baby monitor does not replace it, neither as an app nor as a device. It reports a noise or a dropped connection, nothing more.
Frequently asked questions
Does a baby monitor app need internet?
As long as both phones are on the same Wi-Fi network, no internet is needed. The connection runs directly between the devices, and the router does not have to be online for that. You only need internet once you move away from the child and your phone is on a different network.
Does a baby monitor work over mobile data?
Yes. The device with the child normally stays on the home Wi-Fi while the parent device moves to the mobile network. A relay server connects the two networks. How much data this costs depends mainly on whether the video is running.
Can I connect two phones without Wi-Fi and without mobile coverage?
Not for continuous audio across several rooms. Bluetooth does not suffice in range or in purpose. A hotspot on one of the devices does create a network, but it drains the battery of the device that has to last all night. Where there is neither Wi-Fi nor mobile coverage, a classic baby monitor with its own radio link is the better fit.
Why can the two phones not find each other in a holiday home?
Usually because of a router setting. Either one device is on the guest network and the other on the main network, or the router generally forbids devices on the Wi-Fi from seeing each other. Both are common in unfamiliar networks and can rarely be changed as a guest. In that case the route over mobile data remains.
Will the baby monitor use up all my data?
That depends on the video. Sound alone is economical. If you are monitoring over mobile data, leave the picture switched off and turn it on only when you want to look.