Documented specifications
Algo · Algo retained the 8420 in its current IP-display portfolio, product catalogue and firmware selector at review on October 11, 2026. Exact regional stock, hardware revision, approved firmware, platform entitlement, interoperability and remaining support were not established.
| Specification | Documented value |
|---|---|
| Visual outputs | Two opposite-facing 15.6-inch 1920×1080 LCDs show identical content; they are not documented as independently addressable displays. Each side also has multicolor LED flashers. Source ↗ |
| Audio and microphone | The April 2026 sheet lists six speakers, G.711, G.722 and multicast Opus, an omnidirectional microphone, and 106 dBA at 1 m; the current product-page table lists 100 dB at 1 m. Preserve source revision and measure the installed result. Source ↗ |
| Mounting | The included hollow bracket supports wall or ceiling mounting; structure, rated fasteners, wiring side, bracket attachment, clearance and service access remain installation responsibilities. Source ↗ |
| Power | The October 2026 guide recommends 802.3bt Type 4 and states Type 3 as the minimum. The product page also describes lower-power operation with severe reduction. Use the exact hardware instructions and record negotiated class, device draw and switch budget. Source ↗ |
| SIP roles | The April 2026 sheet lists 50 page, 10 emergency-alert and 10 ring extensions; account entitlement, registration limits, source authorization and each role's actual state require verification. Source ↗ |
| Multicast | RTP multicast send and receive across up to 50 zones is documented, with separate sender, receiver, address, port, codec, priority and visual-screen mapping evidence. Source ↗ |
| Content model | Slides feed screens and event mappings. The two physical LCDs mirror the selected content, so a correct view on one side does not establish the other side's sight line or physical display condition. Source ↗ |
| Input and accessories | A normally open or closed dry-contact relay input can be supervised and used with listed accessories; contact state, end-of-line behavior, action mapping and tamper evidence remain separate acceptance steps. Source ↗ |
| Protection and management | The product material lists TLS, mutual authentication, SRTP, HTTPS, 802.1X, SNMP, RTCP, ADMP and RESTful API capability. Loaded certificates, negotiated sessions, authorization and visible outcomes require separate proof. Source ↗ |
| Environment | The product sheet limits operation to 0–40 °C, 10–95% non-condensing and dry indoor locations; the product with bracket is listed at 11.9 lb / 5.4 kg. Source ↗ |
Unlisted fields remain unverified. Platform compatibility and remaining support life require confirmation for the exact ordered model.
Use two-sided placement for two approach directions
The 8420 is designed for hallways, corridors and open areas where people approach from opposite directions. Confirm both approach paths, mounting height, obstructions, glare, ambient light, text size and maintenance clearance. The two LCDs mirror the same content; they do not create two independently programmed message zones.
Acceptance therefore needs two physical viewing checks even when the configured screen object is shared. A correct image on one side does not prove that the opposite panel, flasher, speaker or sight line is usable.
Treat wall and ceiling mounting as structural work
Algo supplies the device bracket and device-to-bracket hardware, while the installer selects wall- or ceiling-attachment hardware for the actual material. Preserve substrate, rated anchor or fastener choice, stud or joist position, bracket orientation, wiring entry, connector cover, torque or inspection responsibility and the complete 11.9 lb / 5.4 kg device-and-bracket load.
Do not generalize the guide's example fasteners to an uninspected structure. A powered bench test is not evidence that a ceiling or wall installation is secure, code compliant or serviceable.
Resolve the power evidence before feature testing
The October 2026 guide recommends 802.3bt Type 4 and names Type 3 as the minimum for the 8420. The current product page additionally describes PoE+ operation with severely reduced performance, while the April sheet describes Type 4 as recommended and Type 3 as reduced. Keep those revision-sensitive statements visible rather than combining them into one universal minimum.
Use the exact hardware label, current installation instructions and approved firmware. Record PSE class, negotiated class, measured device draw, cable path, LLDP or detection mode, switch budget and which outputs are active. A booted web interface does not prove full brightness, flash or audio performance.
Keep mirrored content and physical outputs separate
Slides, screens and event mappings select the content shown on both LCDs. Record those objects once, then observe each LCD, each flasher bank and each audio direction separately. A stale overlay, failed panel or obstructed side can produce different physical results even though the shared content selection is correct.
Use the display-speaker screen diagnostic for a blank, stale or wrong result. It separates local rendering, event mapping, priority, duration, API overlay, time and downloaded assets before changing the network.
Commission SIP, multicast, input and API paths independently
Page, ring and emergency-alert registrations, multicast send or receive, supervised dry-contact input and RESTful API control use different identities, triggers and authorization boundaries. Preserve the source, destination, content, audio, flash pattern, priority, cancellation and audit evidence for every approved path.
A registered page extension does not prove a ring account, multicast subscription, accessory input or API action. Firmware 5.7 adds display API controls for the 8410 and 8420, but installed firmware, authentication and a successful response remain narrower than a visible result on both sides.
Keep published capability and installed acceptance distinct
The current product page and April sheet publish different maximum acoustic figures. Treat each as a dated manufacturer condition, not an installed promise. Measure intelligibility, level, ambient-noise response, talkback, flash visibility, display readability and synchronization at representative positions under an approved plan.
TLS, mutual authentication, SRTP, supervision and emergency-alert language likewise describe capability, not configured protection or a complete life-safety workflow. No 8420, structural mount, power tier, protected session, visual result, acoustic result, emergency workflow, availability, compatibility or price was independently tested for this reference.
Sources & applicability
Primary references for the technical details above. Operational examples and planning checklists are VoIP.info editorial guidance.
- Algo 8420 product page ↗
- Algo 8420 product sheet dated April 20, 2026 ↗
- Algo 8410 and 8420 user guide updated October 1, 2026 ↗
- Algo current IP-display portfolio ↗
- Algo visual-messaging workflow ↗
- Algo firmware 5.7 release notes ↗
- Algo 8420 firmware selector ↗
Examples require adaptation to your topology. No live PBX or hardware testing is claimed.