There is a phone in your drawer with a better camera than most budget security cameras sold today. It has wifi, a charging port and a lens, which is the entire hardware list. What it has been missing is not a mount or a memory card. It is a way to say what you actually want to be told about.
A four year old midrange handset usually beats a fifty euro security camera on sensor size, low light performance and lens quality, because a phone camera was the headline feature of the device and the camera in a cheap security cam is the cheapest part that will pass. The phone also arrives with a battery, so a brief power cut does not blind it, and with a screen you can use to aim it properly instead of guessing from an app preview.
The practical advantages matter more than the specs:
Most people who try this download an old-phone camera app, get a live stream and motion alerts, and quietly give up two weeks later. The reason is always the same: motion detection reacts to change in the picture, not to meaning. Sun moving across the floor is motion. A curtain in a draught is motion. Headlights through a window at 1am are motion. After forty pointless buzzes you stop reading the alerts, and a camera whose alerts you ignore is a camera that is off.
A live stream has the mirrored problem. It is only useful while you are looking at it, and nobody watches a stream of their own empty hallway all day.
AI Vision Monitor runs the old phone as the eye, and puts a vision AI model behind it that answers the question you typed. You are not choosing from a list of detectable objects, you are writing a sentence:
Because the model reads the scene, a shadow is a shadow and a person is a person. It also keeps earlier frames as context, so a bag that has been sitting in the hallway since morning is not reported as a new event every five minutes.
| Option | Upfront cost | Install | What triggers an alert |
|---|---|---|---|
| Tapo, Wyze and other budget cams | 20 to 50 euro per camera | Mount or stand, plus a wall socket | Motion, plus person detection on some models, often behind a subscription |
| Ring and similar doorbells | 60 to 200 euro, monthly plan for history | Often drilling or wiring, hard in a rental | Motion zones and person detection, tuned with a sensitivity slider |
| Alfred and other old-phone apps | Free, paid tier for quality | None, phone only | Motion detection on pixel change |
| AI Vision Monitor on an old phone | Free credits to start, no subscription | None, phone only | A condition you wrote in your own words |
The honest summary of that table: if you want continuous recording kept locally on an SD card, a cheap dedicated camera does that and this does not. If what you actually want is to be told about one specific thing and left alone the rest of the time, the phone in your drawer is the cheaper and less permanent answer.
With a light AI model (0.5 credits per check) and a check every 5 minutes across a 10-hour workday:
120 checks x 0.5 credits = 60 credits, about 0.08 euro per day on the 2.50 euro starter pack.
Longer intervals cost proportionally less, so a check every 15 minutes over the same day is closer to 0.03 euro. New users get 50 free credits, no card required, which is enough to set the whole thing up and see real alerts before paying anything. There is no subscription.
Get it on Google Play Download on the App Store
This checks the scene on an interval rather than recording continuously, so something that happens entirely between two checks can be missed, and there is no rolling archive to scroll back through. Shorter intervals catch more and cost more, and that trade is yours to set. The phone needs mains power and internet, because the analysis runs server side. Leaving a phone plugged in at 100 percent for months is hard on an old battery, which is a fine fate for a handset you were not using but worth knowing. A dark, grainy night frame is harder for the AI to read than a lit one, exactly as it is for a person. And this is a notification tool, not a monitored alarm system, so it will not call anyone on your behalf.
One more thing worth saying plainly: if you are pointing a camera at a shared hallway, a garden other people use or anywhere your neighbours appear, check your local rules on recording before you do it. Rules on filming shared and public space, and on audio in particular, differ a lot by country.
Does the old phone need a SIM card?
No. Wifi and power are the only requirements. A handset with no service and a cracked screen is fine as long as the camera and the wifi work.
Will this drain or damage the phone?
It runs plugged in, so it will not run flat. Sitting permanently at full charge does age a battery, so use a phone you have genuinely retired rather than a spare you still want later.
Can I use more than one old phone?
Yes, each phone is its own camera with its own sentence, so a hallway phone and a balcony phone can have completely different rules.
What if I would rather use a camera I already own?
You can. A USB webcam, or a wifi and RTSP camera, can be connected through the free companion app for your computer, which keeps your existing hardware and adds the plain-language alerting on top.
Does it work without internet?
No. The device needs a connection because the analysis runs on a server, which is also why a very old phone is enough hardware for it.