Documented specifications
Grandstream · The manufacturer introduced the model in February 2026 and listed general firmware 1.0.1.15 at review; exact regional stock, approved deployment firmware, price and remaining support period were not established.
| Specification | Documented value |
|---|---|
| Speaker output | 50 W; manufacturer states up to 126 dBA maximum SPL Source ↗ |
| Talk-back microphones | Three built-in microphones; manufacturer states an 8 m pickup distance Source ↗ |
| Paging paths | SIP, multicast and group paging; RTSP/HTTP and local playback also listed Source ↗ |
| Ingress and temperature | IP66 rating; listed operating range −30°C to +60°C Source ↗ |
| Power input | 802.3bt PoE++ Class 8 input, up to 71 W Source ↗ |
| Downstream power | 802.3at PoE+ output, up to 25 W Source ↗ |
| Audio codecs | G.711 µ-law/A-law, G.722, G.726-32, iLBC, Opus, G.723 and G.729A/B listed Source ↗ |
Unlisted fields remain unverified. Platform compatibility and remaining support life require confirmation for the exact ordered model.
Start with the paging and talk-back boundary
The GSC3518HS combines a high-output horn, three microphones and several delivery paths. Decide which identities may originate a SIP page, which multicast groups the endpoint may receive, whether talk-back is permitted and whether RTSP/HTTP, local-file, text-to-speech or mobile playback is in scope. These paths have different authentication, network and evidence requirements.
The manufacturer lists call-waiting with priority override. A device priority setting is not evidence of emergency-message governance, certified supervision, redundant power, regulatory compliance or delivery to every occupied area. Keep routine paging, security operations and any life-safety system contractually and technically distinct.
Treat sound output as an exposure limit
The datasheet states a 50 W speaker and maximum sound-pressure level up to 126 dBA. That is a manufacturer maximum, not an instruction to operate at full output. Have a qualified designer set zoning, direction, level caps and permitted schedules for the actual site, and account for workers, nearby residences, reflections and changing ambient noise.
The stated eight-metre microphone pickup distance also needs an occupied-site test. Wind, traffic, mounting height, horn output and privacy expectations can make two-way audio unusable or inappropriate even when the microphones capture sound. Record signage, authorization and retention rules where talk-back may collect conversation.
Validate the outdoor installation
Grandstream lists IP66 ingress protection, a waterproof cable gland, wall or pole mounting, a stainless-steel bracket and an operating range of −30°C to +60°C. Those specifications do not replace a site-specific assessment of orientation, drainage, cable entry, corrosion, lightning and surge protection, structural load, wind, condensation or local electrical rules.
Use the supplied mounting and cable-sealing instructions for the exact hardware revision. Confirm that every unused opening is protected and that maintenance can be performed without exposing people to an active horn or an unsafe work position.
Budget both sides of the PoE chain
The published input is 802.3bt PoE++ Class 8 with a listed maximum of 71 W; the second Ethernet port can provide up to 25 W of 802.3at PoE+ output. Do not subtract label maxima and assume the remainder is available. Confirm the supplying switch or injector, cable length and class negotiation, then include the downstream device and the horn's worst accepted operating state in a measured power budget.
Decide the intended behavior when upstream power, the downstream device, the network or the PBX fails. Cascading a camera or other endpoint through the horn couples their failure and maintenance domains; document that dependency and verify recovery.
Commission each path separately
Record the exact hardware and firmware; the manufacturer firmware directory listed 1.0.1.15 as general firmware at review. Stage updates through an approved change and rollback process. Although the datasheet lists TLS, SRTP, HTTPS, 802.1X, secure boot and encrypted provisioning, the enabled signaling, media and management controls still require inspection on the deployed configuration.
Test SIP paging, multicast scope and priority, talk-back initiation and termination, input/output wiring, permitted streams, intelligibility, level limits, loss of network and power, and restoration. No hardware, acoustic, environmental, ingress, PoE, PBX, multicast, streaming, security, emergency, availability or price behavior was tested for this reference.
Sources & applicability
Primary references for the technical details above. Operational examples and planning checklists are VoIP.info editorial guidance.
- Grandstream GSC3518HS product page ↗
- Grandstream GSC3518HS datasheet ↗
- Grandstream firmware listing ↗
- Grandstream GSC3518HS introduction ↗
Examples require adaptation to your topology. No live PBX or hardware testing is claimed.