VoIP.infoThe independent guide to business communications.
VoIP.info Device reference

Grandstream HT812 v2: two FXS ports, profiles and firmware boundaries

Keep two analog ports, two SIP profiles, integrated routing, registration, T.38, provisioning and the V2 firmware family as separate evidence.

Reviewed 2026-10-24Grandstream exact-model product pages and datasheets, current HT81x V2 administration and user guides, firmware 1.0.15.3 release notes dated September 17, 2026, and the current firmware-upgrade guide were reviewed October 24, 2026. Exact V2 identity, hardware and software component versions, network role, FXS port, SIP profile, SIP identity, registration, hunting-group membership, analog electrical path, signaling, media, fax negotiation, provisioning state and completed call or fax remain separate evidence. Published firmware is not proof of the installed build, provider approval or a successful change. No adapter, analog telephone, fax device, cable, line voltage, ring cadence, caller ID, switch, router, SIP service, PBX, account, packet, call, fax, firmware image, price, availability, compatibility, support entitlement or vendor response was inspected or testedFoundationalDocumentation based · not lab tested

Documented specifications

Open IP Phone Compare →

Grandstream · Grandstream maintains an exact-model product page, current HT81x V2 guides and current V2 firmware records. Those records do not establish local stock, a remaining global support term, provider approval or the build installed on a particular adapter.

HT812 v2: manufacturer-sourced facts
SpecificationDocumented value
Analog ports2 RJ11 FXS ports; physical ports are not SIP profiles, identities or simultaneous calls Source ↗
SIP profiles2 SIP profiles assignable to FXS ports; profile assignment and per-port registration require separate confirmation Source ↗
NetworkTwo 10/100/1000 Ethernet ports; NET1 defaults to WAN and NET2 to LAN, with an integrated NAT-router mode Source ↗
Routing boundaryProduct material states routing up to 100 Mbps; port link speed and routing throughput are different measurements Source ↗
Fax modesT.38 up to 14.4 kbps and G.711 pass-through are listed capabilities, not proof of successful fax negotiation Source ↗
ProvisioningTR-069 and XML provisioning are listed; request, download, apply, reboot and effective state remain separate Source ↗
Firmware familyHT812 V2 uses the HT81x V2 firmware family; release 1.0.15.3 is dated September 17, 2026 Source ↗
Downgrade boundaryAfter 1.0.9.3 or later, downgrade to 1.0.7.5 or earlier is not supported because of CPU-frequency adjustments Source ↗

Unlisted fields remain unverified. Platform compatibility and remaining support life require confirmation for the exact ordered model.

Confirm HT812 V2 before using a file or template

Record the printed HT812 V2 label, part and hardware identifiers, serial or MAC, and every software component version shown on the status page. The original HT812 and HT812 V2 are not interchangeable documentation or firmware targets. A family guide or similarly named binary does not prove that a file matches the unit in hand.

The live product page, current guides and 1.0.15.3 release record establish published evidence, not the installed build, local availability, provider approval or support entitlement.

Keep two FXS ports, two profiles and identities distinct

HT812 V2 exposes two FXS ports and two SIP profiles. Each port can be assigned a profile, while the SIP User ID, Authenticate ID, password and registration result are separate fields and states. Hunting-group behavior can let member ports use an active port account for outbound calls, so a working dial tone or call does not prove that every port independently registered.

Map port, physical analog device, assigned profile, SIP identity, registration, hunting role and intended inbound and outbound behavior before changing credentials.

Treat NET1, NET2 and router mode as a design choice

The guide describes NET1 as WAN and NET2 as LAN by default, with configurable roles and an integrated NAT router. The Ethernet interfaces are Gigabit, while Grandstream states routing performance up to 100 Mbps. Do not convert interface speed into routing throughput or treat this compact router claim as tested edge-firewall capacity.

Record cabling, operating mode, address, gateway, DNS, NTP, upstream NAT and any port forwarding. Then prove provisioning, registration and media separately.

Trace the analog path after registration

The FXS LED can show unregistered, registered, off-hook or busy, and voicemail-indication states. It does not measure line voltage, ring delivery, handset wiring, regional impedance, caller-ID format, DTMF or two-way audio. Use the IVR, reached with three asterisks, and menu 02 to confirm the announced WAN address without treating that as a SIP or call test.

For each port, check the analog device and cable, hook state, dial tone, inbound ring, answer, outbound digits, DTMF, caller ID and bidirectional media in that order.

Qualify T.38 and G.711 fax paths independently

Grandstream lists T.38 relay and G.711 pass-through. Those are configuration capabilities, not proof that the provider, PBX, remote endpoint and network negotiated a reliable fax path. Capture call signaling, any T.38 re-INVITE or SDP, transport, packet loss and the fax devices’ result pages.

A SIP registration, voice call or single short fax does not establish sustained fax compatibility. Preserve modem settings and retry results without claiming laboratory validation.

Stage V2 firmware with the downgrade boundary

Release notes dated September 17, 2026 list HT8xx V2 firmware 1.0.15.3 and identify the HT81x V2 image family used by HT812 V2. The user guide warns that a unit upgraded to 1.0.9.3 or later cannot be downgraded to 1.0.7.5 or earlier because of CPU-frequency adjustments.

Preserve exact identity, current component versions, configuration, source, image, hash from the release record, provider approval, maintenance window and recovery plan. After change, verify the effective build, port assignments, registrations, calls and fax behavior independently.

Sources & applicability

Primary references for the technical details above. Operational examples and planning checklists are VoIP.info editorial guidance.

Examples require adaptation to your topology. No live PBX or hardware testing is claimed.

Continue your research

Troubleshooting · Grandstream exact-model product pages and datasheets, current HT81x V2 administration and user guides, firmware 1.0.15.3 release notes dated September 17, 2026, and the current firmware-upgrade guide were reviewed October 24, 2026. Exact V2 identity, hardware and software component versions, network role, FXS port, SIP profile, SIP identity, registration, hunting-group membership, analog electrical path, signaling, media, fax negotiation, provisioning state and completed call or fax remain separate evidence. Published firmware is not proof of the installed build, provider approval or a successful change. No adapter, analog telephone, fax device, cable, line voltage, ring cadence, caller ID, switch, router, SIP service, PBX, account, packet, call, fax, firmware image, price, availability, compatibility, support entitlement or vendor response was inspected or tested

Grandstream HT812 V2 or HT814 V2 port registers but phone, fax or audio fails

Find the first mismatch across V2 identity, FXS port and profile mapping, hunting, analog wiring, signaling, media, fax negotiation, NAT or firmware.

Read guide →
Device reference · Grandstream exact-model product pages and datasheets, current HT81x V2 administration and user guides, firmware 1.0.15.3 release notes dated September 17, 2026, and the current firmware-upgrade guide were reviewed October 24, 2026. Exact V2 identity, hardware and software component versions, network role, FXS port, SIP profile, SIP identity, registration, hunting-group membership, analog electrical path, signaling, media, fax negotiation, provisioning state and completed call or fax remain separate evidence. Published firmware is not proof of the installed build, provider approval or a successful change. No adapter, analog telephone, fax device, cable, line voltage, ring cadence, caller ID, switch, router, SIP service, PBX, account, packet, call, fax, firmware image, price, availability, compatibility, support entitlement or vendor response was inspected or tested

Grandstream HT814 v2: four FXS ports, profiles and firmware boundaries

Keep four analog ports, two SIP profiles, hunting behavior, integrated routing, fax modes and the V2 firmware family as separate evidence.

Four-port analog telephone adapter with integrated router
Grandstream maintains an exact-model product page, current HT81x V2 guides and current V2 firmware records. Those records do not establish local stock, a remaining global support term, provider approval or the build installed on a particular adapter.

Read guide →
Hub

Grandstream phones

Evaluate Grandstream desk, cordless, analog and facility endpoints by exact model, operational role and supported management path.

Explore topic →
Device category · Current Grandstream ATA and FXS-gateway catalogues plus exact-model documentation reviewed September 27, 2026; no adapter, gateway, analog device, wiring, PBX, provider, fax or call tested

Analog telephone adapters and FXS gateways

Choose FXS port count, analog electrical behavior, SIP identity, power and failure handling before preserving telephone-side devices on an IP service.

Read guide →
Guide · Analog interface and carrier behavior vary by device, region and firmware

FXS vs FXO: connect the right analog roles

Understand line-supplying and line-consuming ports before choosing an ATA or analog gateway.

Read guide →
Guide · Analog interface and carrier behavior vary by device, region and firmware

Connecting an analog phone to VoIP with an ATA

Validate the local analog interface and the IP calling service as separate parts of one deployment.

Read guide →
Guide · Analog interface and carrier behavior vary by device, region and firmware

Fax over VoIP: T.38 relay versus G.711 passthrough

Choose a fax path from end-to-end support and observed document delivery, not a codec checkbox.

Read guide →
Guide · Vendor-neutral workflow; exact parameters and precedence depend on model and firmware

Phone firmware deployment and rollback planning

Upgrade a mixed endpoint estate without assuming every model or intermediate release behaves alike.

Read guide →