# How to turn your building's intercom into a smart intercom > What an intercom retrofit is, how the call reaches your phone, what the visitor needs in order to ring (nothing new) and what happens when the internet drops. - Published: 2026-07-20 - Canonical (HTML): https://doorlink.com.ar/en/blog/como-funciona-portero-inteligente - Versión en español: https://doorlink.com.ar/blog/como-funciona-portero-inteligente.md --- Turning a building's electric intercom into a smart one doesn't mean ripping everything out and starting over. The most expensive part is already installed and working: the street panel and the wiring. A retrofit takes advantage of that and adds the only thing missing — the call reaching your phone. ## What is an intercom retrofit? A retrofit adds electronics to the intercom you already have, instead of replacing it. A module is connected to the existing wiring (the 4+n and 5+n wire systems used by almost every Argentine building) and that module routes the call to your phone. The street panel isn't changed and nothing gets rewired. The panel stays the same panel. The visitor presses your apartment's button exactly as always, and each unit's handset stays on the wall, working. What changes is that the call now has one more path: besides the handset, it rings on your phone. ![Retrofit diagram: the street panel connects over the existing wiring to the DoorLink module, which routes the call over the internet to the app; the indoor handset stays connected as always](https://doorlink.com.ar/blog/retrofit-esquema-en.svg) If you're weighing this option against replacing the whole system, we compare both paths with numbers in [replace or modernize the intercom](https://doorlink.com.ar/en/blog/reemplazar-o-modernizar-portero). ## How does the call reach your phone? When someone rings your apartment, the module takes that call and sends it over the internet to the DoorLink app, which rings on the phone of every resident in the unit. You answer and see and hear the person at the door, live. We designed that screen so answering feels exactly like answering a WhatsApp video call: it rings, you swipe, you talk. No menus, no security jargon. We tested it with older users who had never used this kind of app, with one simple rule: if it needs explaining, it's badly designed. The only new requirement compared to a traditional intercom is that the building has internet, because the video call travels over that connection. In exchange, the call finds you wherever you are: in your apartment, at work, or on vacation. ## How does the door open remotely? From the app, with one button. Behind the scenes it actuates the same electric strike as always: when you tap "open", the module drives the building's door-release circuit exactly the way the handset's button did. The retrofit doesn't invent a new lock. It uses the one that's there, which is why remote opening is exactly as reliable as the building's existing circuit. If it worked fine with the old intercom, it will keep working. And if the strike was already failing, that's a separate fix, as we cover in [why an electric intercom fails](https://doorlink.com.ar/en/blog/portero-electrico-no-funciona). ## What does the visitor need in order to ring? Nothing they don't have today. The delivery rider, the technician, a guest or a kid presses your apartment's physical button the way it's been done forever. No smartphone, no data, nothing to scan, no need to know what system the building runs. This is what separates a retrofit from QR intercoms, where the person on the street needs a phone with a camera and an internet connection just to ring. In a building with constant delivery and visitor traffic, that difference shows up every single day. We dig into it in [physical button or QR code](https://doorlink.com.ar/en/blog/boton-fisico-vs-porteros-qr). ## What if a neighbor doesn't use a smartphone? They keep answering on the handset, like always. The indoor handsets aren't removed: the retrofit adds a path, it doesn't erase the old one. In buildings with neighbors of every age, this avoids the worst assembly argument there is — forcing everyone to adopt an app. For the cases where neither the handset nor the app fits, we're developing internet-connected indoor phones that answer like a traditional handset but talk to the new system underneath. They're not on sale yet. We mention them because they mark where the product is headed: every neighbor answering however they prefer. ## What happens if the internet drops or the phone doesn't ring? It can happen, and we'd rather tell you than have you find out alone. The most common case isn't an intercom failure but the phone itself: "Do Not Disturb" or notification permissions can silence the call. It's worth going into settings once and allowing the app to ring even when the phone is on silent. The other case is an internet outage in the building. The video call travels over that connection, so while the outage lasts, that path is interrupted. The handset doesn't depend on the internet: it keeps ringing, and the visitor can still call because the street button never noticed anything. That's the advantage of modernizing without dismantling what was there: when something fails, the system falls back to the familiar, not to zero. ## Does the building change its appearance? No. The street front stays as it is, with its usual panel. The modernization lives in the residents' phones, not on the wall. For many buildings that's a detail; for others, with decades-old façades that are part of their identity, it's the point that decides the vote. It also simplifies the assembly: nobody has to debate how the façade will look, because it looks the same. ## What other options exist? They exist, and it's worth knowing them. In Argentina there are QR or virtual intercoms, where the visitor scans a code at the door to ring (Tappbell and Bellify are two established names), and complete new systems with video in every unit. Each path has its own logic: QR takes hardware off the wall, a full system renews everything, and a retrofit keeps what works and adds the phone. [Smart intercoms in Argentina](https://doorlink.com.ar/en/blog/porteros-inteligentes-argentina) maps the three families with dated prices, and [physical button or QR code](https://doorlink.com.ar/en/blog/boton-fisico-vs-porteros-qr) compares what each system asks of the visitor standing at the door.