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Grandstream HT813: one FXS phone, one FXO PSTN line and lifeline routing

Keep the device-facing FXS port distinct from the PSTN-facing FXO port, two SIP profiles, WAN and LAN roles, peer or registered routing, lifeline relay and exact-model firmware state.

Reviewed 2026-10-24Grandstream exact-model HT813 product information, datasheet, user and administration guides, FAQ, quick-installation, provisioning and peer-trunk guidance, current firmware index, and firmware 1.0.19.6 release notes dated May 15, 2025 were reviewed October 24, 2026. FXS endpoint, FXO PSTN line, SIP profile, identity, registration, peer trunk, dial plan, forwarding, stage method, WAN or LAN role, NAT, lifeline relay, line supervision, firmware, signaling, media, fax and accepted service remain separate evidence. Published defaults and capabilities do not prove installed configuration, compatibility, capacity, availability, provider approval, regulatory suitability or a successful change. No adapter, analog device, PSTN line, cable, network, PBX, provider account, packet, call, fax, alarm, emergency workflow, outage, firmware image, checksum, price, inventory, support entitlement or vendor response was inspected or testedIntermediateDocumentation based · not lab tested

Documented specifications

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Grandstream · Grandstream maintains a current product record, documentation set and general firmware listing for HT813. Those records do not establish installed hardware or firmware, local availability, provider approval, support entitlement or remaining service life.

HT813: manufacturer-sourced facts
SpecificationDocumented value
Analog roles1 FXS port powers an analog phone or fax; 1 FXO port connects a PSTN or traditional-PBX line. The roles are not interchangeable Source ↗
SIP profiles2 independent SIP profiles are documented, one for FXS and one for FXO; profiles are not ports, calls or proof of registration Source ↗
Network boundaryWAN and LAN are 10/100 interfaces; WAN commonly faces the upstream network while LAN can sit behind the built-in router and DHCP service Source ↗
Lifeline relayThe FXS port can be hard-relayed to the FXO PSTN line after power loss or loss of SIP registration; actual wiring and observed behavior remain separate evidence Source ↗
PSTN routingFXS-to-PSTN access, PSTN-to-VoIP forwarding and VoIP-to-PSTN dialing are separate flows with distinct dial-plan, ring, PIN and stage settings Source ↗
Peer trunkGrandstream documents no-registration peer use with the FXO listener on port 5062 by default; the published example is not an installed configuration Source ↗
Fax capabilityT.38 and G.711 pass-through are documented; negotiation, fallback and delivered pages require end-to-end evidence Source ↗
Firmware identityThe current general listing names 1.0.19.6; release notes dated May 15, 2025 name ht813fw.bin and publish MD5 d4235d4c88bfcb0fe6d50f14cb9377af Source ↗

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

Start at the FXS and FXO boundary

HT813 combines one FXS port for an analog phone or fax with one FXO port for a PSTN or traditional-PBX line. An FXO port does not supply endpoint battery and ringing, and the FXS port is not a carrier-line input. Record the printed model, hardware, serial or MAC, every cable and both port states before moving anything.

Two SIP profiles correspond to separate FXS and FXO functions. They do not by themselves prove registration count, simultaneous-call capacity or any accepted route.

Draw every call direction separately

Map FXS phone to VoIP, FXS phone to PSTN, inbound PSTN to the local phone, PSTN to VoIP forwarding, and VoIP to PSTN access as distinct flows. Preserve redacted identities, registration or peer mode, local SIP ports, access codes, dial plans, ring count, forwarding target, PIN policy and stage method.

A registered FXS profile does not validate the FXO profile, PSTN seizure, line answer, disconnect supervision or forwarding.

Place WAN, LAN and NAT on the diagram

Grandstream documents two 10/100 interfaces. WAN commonly connects to the upstream router or switch; LAN can place a device behind the HT813 router and DHCP service. Record effective device mode, both physical links, addresses, gateway, DNS, time, management path and upstream NAT.

A link LED or reachable web interface does not prove provisioning, SIP signaling, RTP or PSTN service.

Treat lifeline as a physical safety boundary

Grandstream documents a hard relay from FXS to FXO when power or SIP registration is lost. Preserve the actual line on FXO, the phone on FXS, normal-power route and an authorized failure observation separately. Do not assume that a relay label makes an emergency, alarm, lift, medical or regulated service suitable.

Avoid outage tests where disconnecting power or service could place people or property at risk.

Bind provisioning and firmware to the exact model

The current firmware index lists 1.0.19.6 for HT813. Its May 15, 2025 release notes name ht813fw.bin and publish an MD5. The administration guide documents device-specific, model-specific and global configuration request order, plus resynchronization by SIP NOTIFY.

Preserve source, filename, published checksum, transfer result, reboot, installed version, effective configuration and recovery plan. A download or restart is not accepted service.

Accept calls, supervision and fax independently

Pilot each authorized direction for expected line selection, ringing, caller ID, digits, answer, two-way audio and disconnect. Confirm restart persistence and the intended failure route. For fax, capture negotiated mode and successful multi-page delivery in both directions rather than relying on T.38 capability.

No adapter, phone, fax, PSTN line, call, packet, outage or firmware action was tested for this reference.

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 HT813 product information, datasheet, user and administration guides, FAQ, quick-installation, provisioning and peer-trunk guidance, current firmware index, and firmware 1.0.19.6 release notes dated May 15, 2025 were reviewed October 24, 2026. FXS endpoint, FXO PSTN line, SIP profile, identity, registration, peer trunk, dial plan, forwarding, stage method, WAN or LAN role, NAT, lifeline relay, line supervision, firmware, signaling, media, fax and accepted service remain separate evidence. Published defaults and capabilities do not prove installed configuration, compatibility, capacity, availability, provider approval, regulatory suitability or a successful change. No adapter, analog device, PSTN line, cable, network, PBX, provider account, packet, call, fax, alarm, emergency workflow, outage, firmware image, checksum, price, inventory, support entitlement or vendor response was inspected or tested

Grandstream HT813 FXS, FXO, lifeline or PSTN call route fails

Find the first mismatch in physical port role, FXS or FXO SIP profile, PSTN direction, peer or registered routing, WAN or LAN topology, lifeline relay, line supervision or exact-model firmware state.

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Plan inbound routing, line seizure and disconnect supervision for a retained analog service.

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