Start with the riser, not the camera
When people plan to upgrade a video intercom in an existing apartment block, they start by choosing a door station with a nice finish. That is the fourth decision, not the first. The first is what is already inside your walls, because in most buildings that is what determines every other choice.
Old blocks almost never have Ethernet running to the entrance. They have copper that was pulled twenty years ago — and usually one of two topologies:
Four-wire or more (analogue point-to-point). Typically two wires for power/ground, one pair for audio, and a coax or twisted pair for composite video. This is forgiving to replace: each conductor has a defined job, you can identify them by function, and most modern hybrid stations can be adapted.
Two-wire bus. Common in European and Asian blocks from the 1990s onward. Every apartment and the door panel all hang on the same pair, addressed digitally. The catch nobody mentions: bus protocols are generally proprietary. A Commax bus, an Aiphone bus, and a Comelit bus are not interchangeable even though they all use two wires in the same colours. If you are replacing a failed system, you need to know which bus it is before you buy anything.
There is good news in the two-wire case. A great many newer stations support non-polarity two-wire bus operation, which means the installer does not have to worry about which way round. That detail saves more callouts than any feature on the spec sheet.
The honest answer about going IP
Running CAT6 to each apartment is the clean answer. PoE gives you one cable for power and data, the video quality is not limited by analogue modulation, and you get a system that integrates with anything.
It is also usually impossible in an occupied building. There is no riser space, drilling through apartments is disruptive, and the cost lands mostly in labour rather than hardware.
Where IP genuinely pencils in: new-build, or blocks that already have a structured-cabling riser for telecoms. Where it does not: anything you cannot open walls in.
Between those extremes sits the option that gets used most in retrofit — keep the existing riser and swap to a modern two-wire bus system, then add an IP converter or a PoE distribution module if only some apartments need app access.
Power budget is the winter failure
Door stations fail in cold weather more than in heat, and it almost always comes down to power.
A panel with IR LEDs and a heater draws considerably more than its summer idle figure. On a PoE installation, standard 802.3af gives you 15.4 W at the source and about 12.95 W usable at the device. A heated panel plus IR can exceed that. Specify 802.3at (PoE+, 25.5 W at source) for anything outdoors in a cold climate, and check whether the switch feeding it actually has budget left — a 24-port switch with a 130 W supply is not PoE+ on all ports simultaneously.
The symptom of getting this wrong is distinctive and worth knowing: the panel works all summer, then reboots on cold mornings, and the logs show nothing useful.
The lock interface will bite you
Almost every finding here is the same: the door release was not considered.
Three cases, with three requirements:
Electric strike. Usually 12 V or 24 V DC/AC, and draws enough that the intercom's internal relay is borderline at best.
Magnetic lock. Substantially higher holding current and strongly inductive, which is hard on relay contacts.
Motorised or mortice release. Often peaky and brief.
The relay inside most door stations is rated somewhere around 30 V / 1 A, frequently less. That is fine for a small strike and marginal for everything else. Use the station's relay to switch an external supply, not to drive the lock directly. It costs one extra part and removes an entire category of intermittent failures where the lock half-opens then buzzes.
Also confirm NO versus NC before install day. A fail-locked versus fail-unlocked choice belongs to whoever owns the building's fire plan, not to the intercom installer.
Image quality: the entrance is a backlit problem
Building entrances are nearly always backlit — daylight behind the visitor, shadowed face toward the camera. Resolution will not save you there. What helps, in order:
True wide dynamic range. Look for a real figure, 120 dB genuine WDR useful; the "digital WDR" implementations mostly brighten shadows and leave the highlights blown.
Lens angle matched to the doorway. Around 160° gives you the person and the parcel they are holding, but severe barrel distortion at the edges. Narrower around 100° is more natural for a vestibule. Decide which you need before choosing.
**Mechanical IR-cut. **Panel must physically move the infrared filter out of the path at night or your night image is purple. Electronic-only solutions drift colour badly at dusk and dawn, which is exactly when people come home.
Starlight-class sensor over more IR LEDs. Adding LEDs gets you a brighter near-field and a washed-out face. A larger, more sensitive sensor handles a face at two metres better than any lamp count.
Finally: panel ingress rating should match exposure. An open porch is not IP65-necessary; a street-facing doorway without any overhang absolutely is, and the mounting box should be the kind with the gasket channel, not the one with four screws through the faceplate.
We manufacture video intercom hardware for OEM and ODM programmes, so read this as the specification checklist that comes out of our own commissioning rather than neutral advice. Current platform options are on the video intercom manufacturing page, and the CCTV camera range covers the complementary surveillance side of the same installations.
The short version: identify the bus before choosing hardware, budget power for January, and drive the lock from an external supply.
XingLiao builds video intercom platforms, CCTV camera systems and home automation system manufacturing for OEM and ODM programmes. See XingLiao for platforms and specifications.
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