Key takeaways:
- Fermax Duox Plus is a retrofit-focused intercom system that can carry power, audio, video, and data over two non-polarized wires, including suitable legacy cabling.
- Fermax does not publish retail MSRP; cited UK seller examples range from £302 for an audio kit to £954 for a WiFi video kit with a keypad, excluding VAT.
- Duox Plus supports up to 10 panels and 10 guard units per block across up to 100 blocks, but buyers should weigh app-plan rules, 2.4GHz WiFi, limited integrations, and mixed customer feedback.
Disclaimer: ButterflyMX provides these blog posts to help our customers and potential customers make the right business decisions. Our blog posts are based on the information available to us at the time of writing.
Fermax Duox Plus is a wired audio and video intercom family for homes, apartment buildings, and larger residential developments. It may appeal to owners, managers, developers, and installers who want to upgrade an entrance without necessarily replacing suitable two-wire cabling.
This Fermax Duox Plus review covers the models, mobile access, pricing examples, subscription rules, installation needs, capacity, customer feedback, and alternatives. The key decision is not just the outdoor panel: the resident terminal, network setup, and app plan can also change the day-to-day experience and total cost.
This guide will answer:
- Fermax Duox Plus review overview
- Models and components
- Features and access options
- How much does Fermax Duox Plus cost?
- Installation, connectivity, and capacity
- Pros, cons, and customer feedback
- Is Duox Plus a good fit?
- Alternatives
- Fermax Duox Plus vs. ButterflyMX
- Frequently asked questions
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Fermax Duox Plus review overview
Fermax Duox Plus is a digital door-entry family that carries power, data, audio, and video over two non-polarized wires. Because the wires do not have positive and negative terminals to match, installers may be able to reuse suitable legacy cables more easily.
The range includes outdoor panels, indoor monitors and telephones, guard units, access-control modules, and preconfigured kits. A guard unit is a desk or reception device for staff who handle entrance calls. Core intercom functions work locally without internet, while DuoxMe call forwarding requires a compatible WiFi or Connect 4G setup.
Who is Fermax Duox Plus designed for?
Fermax positions Duox Plus for single-family homes, small offices, apartment buildings, gated communities, and multi-block residential developments. The same two-wire family can support a simple home entrance or a much larger property.
That flexibility makes configuration important. Buyers need to select an outdoor panel, resident terminal, power supply, mounting hardware, and any keypad or card-reader modules. Mobile service rules also differ between WiFi monitors and non-WiFi Connect 4G terminals.
Fermax company background
Fermax was founded in 1949 in Valencia, Spain. Ardian announced its investment in Fermax in December 2025, and the acquisition was completed in 2026 after prior ownership by MCH Private Equity and Eurazeo.
The ownership change may shape future strategy, but buyers should assess the current hardware, local installer support, service terms, and property fit on their own merits.
Fermax Duox Plus models and components
Duox Plus is a product family, not a single device. Cora and Skyline are entrance panels with different strengths, while Iris and VEO-XL are resident monitors with different interfaces. The WiFi Video Guard Unit is for staffed entrances, not individual apartments.
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IP and IK ratings measure different protections. IP measures resistance to dust and water, while IK measures impact resistance. Cora is rated IP65/IK08. Fermax also offers a 316L stainless-steel Marine panel rated IP54/IK09 for entrances where impact resistance is a priority.
Choose components based on the entrance and resident experience you need. Cora emphasizes an integrated display and outdoor protection, Skyline emphasizes modularity, Iris offers touchscreen controls, and VEO-XL uses physical buttons. Ask the installer to confirm that each quoted feature applies to the exact panel-and-monitor combination.
Fermax Duox Plus features and access options
Fermax Duox Plus combines visitor calling with optional mobile answering, image capture, PIN or proximity credentials, and concierge tools. The available workflow depends on the outdoor panel, resident terminal, and connectivity option selected.
Visitors can call an indoor monitor through the entrance panel. In compatible configurations, DuoxMe can forward the call to a resident’s phone or tablet so the resident can view the visitor, answer, and release the door remotely. Photocaller can capture a visitor image for later review.
Access options include Memokey PIN entry, proximity or Mifare card readers, and remote unlock through DuoxMe. Memokey supports up to 100 PIN codes, making it better suited to smaller credential sets than to an assumption of unrestricted building-wide access management.
Mobile access and visitor calling
DuoxMe service is included with compatible WiFi monitors, which connect through the resident’s home network. Non-WiFi terminals rely on a communal Connect 4G panel and follow a separate free and paid service structure.
WiFi-monitor call forwarding requires a 2.4GHz WiFi network. Homes using a 5GHz-only network or a tightly configured mesh network may need changes before mobile calling works as intended.
ButterflyMX also supports video intercom calls, remote visitor access, and smartphone-based entry. The difference is scope: DuoxMe extends compatible Fermax terminals to a phone, while ButterflyMX provides mobile and visitor access as part of a broader property access platform.
Security, accessibility, and smart-home compatibility
Fermax offers weather-resistant and impact-resistant entrance panels, along with inductive-loop variants for selected panels and monitors. An inductive loop sends audio to compatible hearing aids, which can make entrance communication more accessible.
Amazon Alexa and Google Home are documented for WiFi terminals, but not for Connect 4G terminals. Buyers who need a broader smart-home setup should ask the installer to document the exact integration workflow before selecting hardware.
Some users report problems connecting Ring and similar devices to Duox Plus wiring or protocols. These are user reports, not a universal result for every installation, so an installer should assess the intended device combination.
ButterflyMX supports access control, mobile access, and wallet-based credentials on compatible devices. Buyers can compare that approach with Fermax PINs, proximity or Mifare credentials, and app-based remote unlock.
How much does Fermax Duox Plus cost?
Fermax does not publish a universal retail price for Duox Plus. UK reseller examples list single-family kits from £302 for audio to £954 for WiFi video with a keypad, excluding VAT. These are third-party seller examples, not Fermax MSRP or prices for every market.
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Multi-unit pricing varies by the number and type of panels, monitors, power supplies, mounting boxes, access modules, guard units, and installation work. Suitable existing wiring may reduce cable-replacement work in an older building, but there is no standard installation price.
Does Fermax require a subscription?
No single subscription rule applies to every Fermax terminal. WiFi monitor owners receive DuoxMe service without a separate service fee, while non-WiFi Connect 4G terminals have a capped free plan and an optional paid plan.
Under the Connect 4G service plans, the free tier allows four mobile door openings and four call forwards per month for one user. Regular remote use could exceed that allowance. The paid plan adds unlimited usage, image capture, auto-on, and up to five guest users, but its price appears only inside the app.
Installation, connectivity, and system capacity
Fermax Duox Plus uses two non-polarized wires to carry power, audio, video, and data. A typical installation needs an outdoor panel, a power supply, an indoor monitor or telephone, and a mounting box. Professional installation is standard practice, especially in multi-unit buildings.
A riser is the shared vertical cable path that connects building floors. Fermax documents two simultaneous audio and video channels per riser. That can reduce busy-line conflicts, but larger properties should have an installer map risers, distances, regenerators, power supplies, and expected call traffic before approving the design.
How large can a Duox Plus system be?
Fermax documents support for up to 10 panels and 10 guard units per block, with up to 100 blocks or sub-blocks. Those limits put Duox Plus well beyond a single-home kit.
Capacity is only one part of the design. Property teams should also consider entrance locations, staffed desks, resident terminal counts, signal distances, simultaneous-call needs, and whether each home will use WiFi or Connect 4G service.
Fermax Duox Plus pros, cons, and customer feedback
Fermax Duox Plus offers a compelling retrofit option and a broad hardware range. Still, pricing transparency, service tiers, network requirements, integrations, and customer-reported reliability concerns deserve close attention.
Fermax Duox Plus pros
- Retrofit-friendly wiring: Two non-polarized conductors may reuse suitable legacy cable and reduce the need for new wiring routes.
- Included mobile service for WiFi monitors: Compatible WiFi terminals receive DuoxMe call forwarding without the Connect 4G paid plan.
- Large-property capacity: Published limits cover multiple panels, guard units, risers, and up to 100 blocks or sub-blocks.
- Durable panel choices: Cora emphasizes weather protection, while Marine provides a higher impact rating.
- Several access options: Buyers can combine video calling with PINs, proximity or Mifare credentials, mobile unlock, and selected inductive-loop hardware.
Fermax Duox Plus cons
- No public manufacturer MSRP: Buyers need reseller or installer quotes instead of one standard system price.
- Restrictive Connect 4G free tier: Four openings and four call forwards per month may not cover routine mobile use.
- 2.4GHz network requirement: WiFi call forwarding may require changes to some home or mesh networks.
- Limited documented smart-home support: Official support centers on Alexa and Google Home for WiFi terminals.
- Mixed independent feedback: Customer reports include app, hardware, and support problems, although experiences vary.
What customers say about Fermax
Trustpilot displayed a 2.1 out of 5 rating across 46 Fermax reviews. Recurring complaints mentioned video or gate-control problems, slow support follow-up, and unresolved hardware issues. Some reviewers also praised individual support staff for clear technical help.
These company-wide reviews are not controlled tests of the current Duox Plus family. Treat them as a risk signal, not proof that every installation will have the same result. Buyers should ask who provides first-line support, what service commitments apply, and how app or hardware faults will be handled after installation.
Is Fermax Duox Plus a good fit for your property?
Fermax Duox Plus may be a good fit for a property that wants a wired intercom, has reusable two-conductor cabling, and can secure qualified local installation and support. It is especially relevant when avoiding a full rewire is a major goal.
Before adding Duox Plus to a shortlist, consider:
- Can the existing cable support the proposed design, or will the project need new runs and regenerators?
- Does each entrance need Cora durability, Skyline modularity, Marine impact resistance, or a simpler panel?
- Do residents prefer Iris touchscreens, VEO-XL buttons, telephones, or another terminal?
- Will homes use WiFi monitors or Connect 4G terminals, and what does that choice mean for app costs?
- Can every participating home provide reliable 2.4GHz WiFi?
- Are PINs, proximity credentials, Mifare cards, and remote unlock enough for the property’s access workflow?
- How many entrances, guard desks, blocks, risers, and simultaneous calls must the system handle?
- Does the local installer offer acceptable commissioning, training, warranty, and ongoing support?
Duox Plus centers on entrance panels, resident terminals, guard units, and related access modules. Properties choosing between a focused intercom and a broader access system may also consider ButterflyMX, which combines video intercoms with access control, mobile and visitor access, vehicle access, elevator controls, security cameras, package rooms, smart lock integrations, and wallet-based credentials.
Fermax Duox Plus alternatives
Relevant alternatives include 2N, Aiphone, Comelit, and BAS-IP. The best shortlist depends on whether the project favors a retrofit-oriented two-wire system, an IP intercom that communicates over a data network, or a broader access platform.
- 2N IP Verso or IP Force: Consider 2N for commercial or multi-unit projects evaluating a network-based intercom and a broader integration approach.
- Aiphone IXG: Aiphone is an established intercom option often evaluated for commercial and institutional applications.
- Comelit intercom systems: Comelit is relevant to residential buyers comparing another European audio and video door-entry family with app-oriented options.
- BAS-IP: BAS-IP is a network-based intercom vendor that publishes comparisons involving Fermax systems. Compare the exact BAS-IP and Fermax lines rather than mixing Duox Plus with Fermax’s separate Meet IP range.
An industry overview of business intercom systems can help create a wider shortlist, but final decisions should rely on current manufacturer documents and project-specific quotes.
Fermax Duox Plus vs. ButterflyMX
Fermax Duox Plus and ButterflyMX can both support video entry and remote visitor access, but they take different approaches. Duox Plus is a component-based two-wire door-entry family, while ButterflyMX combines video intercoms with other property access and security products in one platform.
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Neither approach is best for every property. Duox Plus may stand out when reusing two-wire infrastructure is the main goal. ButterflyMX may merit closer evaluation when the project needs video entry alongside broader mobile, visitor, vehicle, elevator, package, camera, or smart-lock workflows.
Frequently asked questions about Fermax Duox Plus
What is Fermax Duox Plus?
Fermax Duox Plus is a digital audio and video door-entry family that carries power, data, sound, and video over two non-polarized wires. It includes outdoor panels, resident monitors and telephones, guard units, access modules, and preconfigured kits.
How much does a Fermax Duox Plus system cost?
Fermax does not publish a universal retail price. Cited UK seller examples range from £302 for a one-way audio kit to £954 for a WiFi video kit with a keypad, excluding VAT; multi-unit systems need project-specific quotes.
Does Fermax Duox Plus require a subscription?
WiFi monitors include DuoxMe service, but non-WiFi Connect 4G terminals use a capped free plan or a paid unlimited plan. The free plan allows four mobile openings and four call forwards per month for one user.
Can Fermax Duox Plus use existing wiring?
Yes. Duox Plus may reuse suitable legacy or bell wiring because it runs over two non-polarized conductors. An installer still needs to inspect cable condition, distances, power, and the overall system design.
Does Fermax Duox Plus need internet or WiFi?
Core local intercom functions do not require internet, but mobile call forwarding does. WiFi monitors require a 2.4GHz home network, while non-WiFi terminals depend on a communal Connect 4G panel.
How many entrances and buildings can Duox Plus support?
Duox Plus supports up to 10 panels and 10 guard units per block and up to 100 blocks or sub-blocks. It also supports two simultaneous audio and video channels per riser.
Does Fermax Duox Plus work with Alexa or Google Home?
Alexa and Google Home are documented for WiFi terminals. These integrations are not available for non-WiFi Connect 4G terminals.
Is Fermax Duox Plus compatible with Ring?
Some users report incompatibility between Ring devices and Duox Plus wiring or protocols. Because those reports are not a universal manufacturer statement, buyers should have an installer assess the exact devices and wiring.
What do customers say about Fermax reliability?
Trustpilot displayed a 2.1 out of 5 company rating across 46 reviews, with recurring complaints about app behavior, gate or video controls, hardware faults, and slow support. Those reviews cover Fermax broadly and are not limited to current Duox Plus installations.
Final verdict on Fermax Duox Plus
Fermax Duox Plus belongs on the shortlist for properties that want a wired video or audio intercom and may benefit from reusing two-conductor cabling. Its panels, monitors, access modules, guard units, and multi-block capacity offer many ways to configure a system.
The central tradeoff is that configuration choices affect far more than appearance. WiFi versus Connect 4G changes mobile-service terms, 2.4GHz networking affects call forwarding, and final costs depend on project hardware and installation. Mixed app and support feedback also makes local installation and after-sales service an important part of the decision.
Compare complete quotes, resident and visitor workflows, network requirements, credential options, and support responsibilities before choosing. If your property also needs a wider set of access and security workflows, consider ButterflyMX alongside Fermax and other intercom alternatives.
Explore ButterflyMX to compare video intercom, mobile access, visitor access, access control, and other property-wide capabilities for your project.
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