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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.

Reviewed 2026-10-27Analog interface and carrier behavior vary by device, region and firmwareIntermediateDocumentation based · not lab tested

Two different transport approaches

G.711 passthrough carries the fax tones through an audio path. T.38 defines real-time Group 3 facsimile communication over IP, allowing compatible gateways to relay fax information rather than treating the entire exchange as ordinary speech audio. An ATA advertising T.38 does not establish support across the PBX, carrier and remote gateway. A path can begin as audio and attempt to switch after fax detection, so inspect the actual session negotiation.

Verify the transition and fallback

Look for the relevant session update and its accepted media description. If the T.38 request is rejected, determine whether a supported G.711 fallback occurs or the call fails. Do not infer that a selected GUI preference became the active transport. For passthrough, avoid unexpected lossy transcoding and investigate packet loss, timing and media processing that can disturb modem tones. Device guidance may recommend specific settings; apply them to the exact firmware and test rather than treating one generic fax recipe as universal.

Test documents, not just tones

Send and receive representative multi-page documents with the intended remote destinations. Record page count, negotiated mode, completion result and any retry. Hearing fax tones or receiving the first page does not establish reliable service. Keep error-correction and speed changes evidence-driven. Reducing speed can help isolate a problem but may hide an unreliable path. For critical document workflows, compare a supported fax service or another agreed delivery method with maintaining the analog machine. Choose based on measured delivery needs and operating responsibility.

Read the mode selected by an Asterisk fax session

The Asterisk res_fax guide keeps T.38 negotiation, allowed or forced audio behavior and the reported FAXMODE independently observable instead of treating capability as use.

Inspect a documented RTP-to-UDPTL transition

Use the T38Fax negotiation diagnostic to correlate the initial G.711 phase, T.38 re-INVITE, SDP answer, UDPTL packets, ECM and document result.

Separate Clearfly managed fax from trunk fax transport

Clearfly lists fax-to-email or eFax-to-email. The provider record does not convert that managed product into evidence for T.38, audio pass-through, an ATA or an existing fax machine.

Keep gateway fax configuration subordinate to end-to-end proof

The GXW4200 v2 family guide separates T.38 or G.711 selection from actual document completion.

Do not convert LES.NET fax-to-email into T.38 evidence

The LES.NET provider record keeps the separate fax service, trunk codec negotiation and completed fax result distinct.

Treat HT81x V2 fax modes as negotiation choices

The HT812 V2 and HT814 V2 list T.38 and G.711 pass-through, while the diagnostic requires live negotiation evidence.

Do not infer fax from Grandstream V2 registration

Both HT802 V2 and HT818 V2 list T.38, but live negotiation and delivered pages remain separate evidence.

Do not infer fax delivery from a listed HT8x1 capability

Grandstream lists T.38 for HT841 and HT881, but negotiated mode and delivered pages remain separate evidence.

Verify HT813 fax mode and delivery separately

Grandstream documents T.38 and G.711 pass-through for HT813; negotiation and delivered pages remain end-to-end evidence.

Do not infer Cloudli fax success from trunk registration

The Cloudli guide keeps T.38 entitlement, negotiation, audio fallback and completed pages separate from voice registration.

Bind Orange T.38 evidence to current project support

The Orange Business Talk guide preserves guide date, ordered service, negotiation, UDP behavior and completed pages without inferring fax support from voice.

Treat the AMI session type as runtime evidence

The AMI fax-session guide records G.711 or T.38 from an active entry without turning the mode label into delivery proof.

Treat Optus T.38 channels as application evidence

The Optus Evolve Voice diagnostic proves fax negotiation, packet flow and completed pages rather than inferring them from Active Channels.

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

Provider research · Current IDT Express DID, SIP Trunking, trunk-group API and provider pages were reviewed October 23, 2026. Public documentation does not define every account's outbound interconnect, SIP authentication, registration, TLS, SRTP, emergency, capacity or commercial state. No IDT Express account, API credential, SIP credential, order, DID, trunk group, switch, address, packet, PBX, firewall, call, media stream, fax, failover event, emergency workflow, price, availability, compatibility or support response was inspected or tested

IDT Express SIP Trunking: DID, trunk-group, switch and PoP evidence

Map API environment, DID assignment, default fallback, ring type, ordered switch targets, PoP, inbound source, media and unresolved account controls without treating one state as proof of another.

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Troubleshooting · Current IDT Express DID, SIP Trunking, trunk-group API and provider pages were reviewed October 23, 2026. Public documentation does not define every account's outbound interconnect, SIP authentication, registration, TLS, SRTP, emergency, capacity or commercial state. No IDT Express account, API credential, SIP credential, order, DID, trunk group, switch, address, packet, PBX, firewall, call, media stream, fax, failover event, emergency workflow, price, availability, compatibility or support response was inspected or tested

IDT Express DID routes to the wrong switch or inbound calls fail

Trace one failed inbound call through API environment, DID assignment, default fallback, ring type, switch order, PoP, source filtering, PBX routing and media.

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

Fax-over-VoIP troubleshooting by failure stage

Distinguish call setup, fax negotiation, page transfer and completion failures.

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Reference · SIP standards; extension support depends on both peers

SIP re-INVITE and UPDATE: changing a session

Read hold, media changes and negotiation conflicts within an existing call.

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Guide

G.711, PCMA and PCMU

Recognize G.711 payloads and calculate their network cost correctly.

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Guide · Asterisk 22 FAXOPT, ReceiveFAX and SendFAX documentation plus branch 22 res_fax configuration and implementation reviewed October 13, 2026; the installed Asterisk version, res_fax module, technology resource, configuration, channel, TIFF/F file, signaling, T.38 negotiation, audio path, session result, storage and delivery remain deployment specific, and no host, module, file, channel, packet, fax session or document was inspected or tested

Asterisk res_fax: session options, mode and result evidence

Keep the generic res_fax layer, loaded technology resource, per-session FAXOPT policy, TIFF/F file, audio or T.38 mode and final transmission result independently observable.

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Troubleshooting · Asterisk 22 FAXOPT, ReceiveFAX and SendFAX documentation plus branch 22 res_fax configuration and implementation reviewed October 13, 2026; the installed Asterisk version, res_fax module, technology resource, configuration, channel, TIFF/F file, signaling, T.38 negotiation, audio path, session result, storage and delivery remain deployment specific, and no host, module, file, channel, packet, fax session or document was inspected or tested

Asterisk ReceiveFAX or SendFAX fails or uses the wrong mode

Trace one fax from the exact channel and loaded res_fax stack through FAXOPT inputs, file access, audio or T.38 negotiation, application result and downstream artifact handling.

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Troubleshooting · T38Fax testing, firewall, SIP ALG, packet-capture, ECM and fax-only service pages reviewed October 13, 2026; the exact trunk, endpoint, intermediary, authentication, registration, SIP dialog, re-INVITE owner, SDP, NAT, firewall, ALG, UDPTL packets, fax speed, resolution, ECM result, duration and received document remain deployment specific, and no account, endpoint, PBX, SBC, firewall, packet, call, fax session or document was inspected or tested

T38Fax call connects but T.38 is not negotiated

Trace one fax from the initial SIP dialog and G.711 phase through the T.38 re-INVITE, SDP answer, UDPTL path, ECM state and received-document result.

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Provider research · Current Clearfly service, FAQ, partner, support and legal pages reviewed October 15, 2026; authentication, registrar and proxy values, DNS behavior, codecs, DTMF, RTP ranges, signaling and media protection, T.38, emergency behavior, capacity limits, routing triggers, current availability, compatibility, exact pricing and support performance remain order specific, and no account, quote, credential, number, port, PBX, endpoint, circuit, portal session, packet, media stream, failover event, load exercise, message, emergency call or live call was inspected or tested

Clearfly SIP trunking: service scope, portal controls and acceptance boundaries

Scope Clearfly trunk quantity, number services, routing features, portal controls, support and unresolved technical handoff to the exact partner-managed order.

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Device family guide · Current Grandstream GXW4200 Series product, datasheet, user-manual, installation, FAQ, firmware, GDMS and provisioning documentation reviewed October 23, 2026; exact hardware revision, regional SKU, stock, support term, approved firmware, rollback path, PBX or provider policy, credentials, cabling, analog load, caller-ID behavior, fax path, hunt design, power, network and failover behavior remain deployment specific; no gateway, analog endpoint, cabling, RJ21 assembly, PBX, profile, credential, registration, hunt group, provisioning job, firmware image, fax, DTMF, call, media stream, power event or failover was inspected or tested

Grandstream GXW4200 v2 FXS gateways: ports, profiles and firmware boundaries

Plan GXW4216, GXW4224, GXW4232 and GXW4248 v2 deployments without confusing analog ports, SIP profiles, account registration, hunting, provisioning or firmware lanes.

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Troubleshooting · Current Grandstream GXW4200 Series product, datasheet, user-manual, installation, FAQ, firmware, GDMS and provisioning documentation reviewed October 23, 2026; exact hardware revision, regional SKU, stock, support term, approved firmware, rollback path, PBX or provider policy, credentials, cabling, analog load, caller-ID behavior, fax path, hunt design, power, network and failover behavior remain deployment specific; no gateway, analog endpoint, cabling, RJ21 assembly, PBX, profile, credential, registration, hunt group, provisioning job, firmware image, fax, DTMF, call, media stream, power event or failover was inspected or tested

Grandstream GXW4200 v2 port registers but rings wrong port or cannot call

Trace one GXW4200 v2 analog port from cabling and hook state through profile, identity, registration, hunting, PBX routing and media without treating Registered as end-to-end proof.

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Provider research · Current first-party LES.NET voice, portal, product, DID, termination, rate-directory, company and support material was reviewed October 23, 2026. Trunk objects, outbound permission, caller identity, DIDs, inbound destination, telephone-number forwarding, per-DID channel labels, provider attempt, PBX match, answer and media remain separate evidence. Public CAD prices, included-feature labels and fraud-detection language are documentation snapshots rather than an account quote, SLA or measured result. No LES.NET account, portal session, trunk, credential, registration, number, port order, destination, forwarding rule, channel entitlement, caller identity, emergency record, message, fax, PBX, DNS answer, firewall, packet, CDR, call, media stream, outage, failover event, price, availability, compatibility or support response was inspected or tested

LES.NET SIP trunking: trunks, DID destinations, channels and call evidence

Separate trunk objects, outbound permission, caller identity, DID destinations, channel labels, forwarding, provider attempts and observed calls.

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Troubleshooting · Current first-party LES.NET voice, portal, product, DID, termination, rate-directory, company and support material was reviewed October 23, 2026. Trunk objects, outbound permission, caller identity, DIDs, inbound destination, telephone-number forwarding, per-DID channel labels, provider attempt, PBX match, answer and media remain separate evidence. Public CAD prices, included-feature labels and fraud-detection language are documentation snapshots rather than an account quote, SLA or measured result. No LES.NET account, portal session, trunk, credential, registration, number, port order, destination, forwarding rule, channel entitlement, caller identity, emergency record, message, fax, PBX, DNS answer, firewall, packet, CDR, call, media stream, outage, failover event, price, availability, compatibility or support response was inspected or tested

LES.NET DID route, channel or outbound SIP call fails

Find the first mismatch across trunk ownership, outbound permission, caller identity, DID destination, channel state, provider attempt, PBX match and media.

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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 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.

Two-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.

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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.

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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.

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Device reference · Grandstream exact-model HT802 V2 and HT818 V2 product pages and datasheets, current HT80x V2 and HT81x V2 administration and user guides, and firmware 1.0.15.3 release notes dated September 17, 2026 were reviewed October 24, 2026. Exact V2 model, hardware, component versions, firmware binary family, network topology, FXS port, profile, identity, registration, hunting role, analog behavior, signaling, media, fax mode, provisioning state and accepted service remain separate evidence. Published firmware and management capabilities do not prove the installed build, provider approval, successful change, compatibility, capacity or availability. No adapter, analog device, cable, line condition, network, VLAN, router, account, PBX, packet, call, fax, image, checksum, price, inventory, support entitlement or vendor response was inspected or tested

Grandstream HT802 V2: two FXS ports, single Ethernet and firmware identity

Keep two analog ports and profiles separate from the single 10/100 network interface, effective provisioning, registration, media and the HT80x V2 firmware image.

Two-port analog telephone adapter
Grandstream maintains an exact-model product page, current HT80x V2 guides and current V2 firmware records. Those records do not establish local inventory, global remaining support, provider approval or the build installed on an individual adapter.

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Device reference · Grandstream exact-model HT802 V2 and HT818 V2 product pages and datasheets, current HT80x V2 and HT81x V2 administration and user guides, and firmware 1.0.15.3 release notes dated September 17, 2026 were reviewed October 24, 2026. Exact V2 model, hardware, component versions, firmware binary family, network topology, FXS port, profile, identity, registration, hunting role, analog behavior, signaling, media, fax mode, provisioning state and accepted service remain separate evidence. Published firmware and management capabilities do not prove the installed build, provider approval, successful change, compatibility, capacity or availability. No adapter, analog device, cable, line condition, network, VLAN, router, account, PBX, packet, call, fax, image, checksum, price, inventory, support entitlement or vendor response was inspected or tested

Grandstream HT818 V2: eight FXS ports, two profiles and routed topology

Keep eight analog ports distinct from two SIP profiles, dual-Gigabit routing, hunting, line-test evidence, provisioning and the HT81x V2 firmware image.

Eight-port FXS gateway with integrated NAT router
Grandstream maintains an exact-model product page, current HT81x V2 guides and current V2 firmware records. Those records do not establish local inventory, global remaining support, provider approval or the build installed on an individual gateway.

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Troubleshooting · Grandstream exact-model HT802 V2 and HT818 V2 product pages and datasheets, current HT80x V2 and HT81x V2 administration and user guides, and firmware 1.0.15.3 release notes dated September 17, 2026 were reviewed October 24, 2026. Exact V2 model, hardware, component versions, firmware binary family, network topology, FXS port, profile, identity, registration, hunting role, analog behavior, signaling, media, fax mode, provisioning state and accepted service remain separate evidence. Published firmware and management capabilities do not prove the installed build, provider approval, successful change, compatibility, capacity or availability. No adapter, analog device, cable, line condition, network, VLAN, router, account, PBX, packet, call, fax, image, checksum, price, inventory, support entitlement or vendor response was inspected or tested

Grandstream HT802 V2 or HT818 V2 has missing ports, wrong network mode or failed firmware

Find the first mismatch in exact V2 identity, expected port count, single-interface versus routed topology, profile mapping, provisioning or firmware binary family.

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Device reference · Grandstream exact-family HT841 and HT881 product information, datasheet, September 2026 user manual, FAQ, quick-installation and provisioning guidance, firmware 1.0.11.8 release notes dated August 14, 2026, and the UCM interconnection guide updated May 4, 2026 were reviewed October 24, 2026. Model, hardware, FXO line, FXS device, SIP profile, identity, registration, peer trunk, port mapping, PBX route, PSTN state, lifeline mode, firmware, provisioning, signaling, media, fax and accepted service remain separate evidence. Grandstream sources conflict on whether the two Ethernet ports are 10/100 or 10/100/1000; exact hardware, negotiated link and interface status must be inspected rather than inferred. Published defaults and capabilities do not prove installed configuration, compatibility, capacity, availability, provider approval or a successful change. No gateway, line, analog device, cable, network, PBX, account, packet, call, fax, outage, firmware image, checksum, price, inventory, support entitlement or vendor response was inspected or tested

Grandstream HT841: four FXO lines, one FXS port and lifeline mapping

Keep four PSTN-facing FXO ports distinct from the single FXS device port, three SIP profiles, per-port routing, bridge or router mode, lifeline relay and HT8x1 firmware state.

Four-port FXO gateway with one FXS port
Grandstream maintains a current shared product record, September 2026 manual and August 2026 firmware record. Those records do not establish installed hardware or firmware, local availability, provider approval, support entitlement or remaining service life.

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Device reference · Grandstream exact-family HT841 and HT881 product information, datasheet, September 2026 user manual, FAQ, quick-installation and provisioning guidance, firmware 1.0.11.8 release notes dated August 14, 2026, and the UCM interconnection guide updated May 4, 2026 were reviewed October 24, 2026. Model, hardware, FXO line, FXS device, SIP profile, identity, registration, peer trunk, port mapping, PBX route, PSTN state, lifeline mode, firmware, provisioning, signaling, media, fax and accepted service remain separate evidence. Grandstream sources conflict on whether the two Ethernet ports are 10/100 or 10/100/1000; exact hardware, negotiated link and interface status must be inspected rather than inferred. Published defaults and capabilities do not prove installed configuration, compatibility, capacity, availability, provider approval or a successful change. No gateway, line, analog device, cable, network, PBX, account, packet, call, fax, outage, firmware image, checksum, price, inventory, support entitlement or vendor response was inspected or tested

Grandstream HT881: eight FXO lines, one FXS port and lifeline mapping

Keep eight PSTN-facing FXO ports distinct from the single FXS device port, three SIP profiles, per-port routing, bridge or router mode, lifeline relay and HT8x1 firmware state.

Eight-port FXO gateway with one FXS port
Grandstream maintains a current shared product record, September 2026 manual and August 2026 firmware record. Those records do not establish installed hardware or firmware, local availability, provider approval, support entitlement or remaining service life.

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Troubleshooting · Grandstream exact-family HT841 and HT881 product information, datasheet, September 2026 user manual, FAQ, quick-installation and provisioning guidance, firmware 1.0.11.8 release notes dated August 14, 2026, and the UCM interconnection guide updated May 4, 2026 were reviewed October 24, 2026. Model, hardware, FXO line, FXS device, SIP profile, identity, registration, peer trunk, port mapping, PBX route, PSTN state, lifeline mode, firmware, provisioning, signaling, media, fax and accepted service remain separate evidence. Grandstream sources conflict on whether the two Ethernet ports are 10/100 or 10/100/1000; exact hardware, negotiated link and interface status must be inspected rather than inferred. Published defaults and capabilities do not prove installed configuration, compatibility, capacity, availability, provider approval or a successful change. No gateway, line, analog device, cable, network, PBX, account, packet, call, fax, outage, firmware image, checksum, price, inventory, support entitlement or vendor response was inspected or tested

Grandstream HT841 or HT881 routes the wrong PSTN line, loses lifeline or stops calls after firmware

Find the first mismatch in FXO versus FXS role, per-port SIP and PBX routing, bridge or router mode, physical lifeline mapping, activation state or HT8x1 firmware evidence.

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Device reference · 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: 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.

Hybrid ATA with one FXS port and one FXO port
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.

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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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Provider research · Cloudli SIP-trunk product, babyTEL rebrand, portal registration, configuration-guide, firewall, capacity, continuity, 911 and terms records reviewed October 25, 2026; Cloudli is the current brand and legacy babyTEL examples remain bounded historical references, while the selected account, region, plan, portal parameters, device guide, network, PBX and current support acceptance govern; no Cloudli or babyTEL account, order, portal, parameter, credential, trunk, registration, NAT mapping, PBX, SBC, firewall, packet, number, call, fax, media stream, continuity event, 911 result, price, availability, compatibility or support response was inspected or tested

Cloudli SIP Trunking: babyTEL transition, registration and continuity evidence

Use the current Cloudli identity, portal-issued SIP parameters, NAT behavior, capacity, service continuity and 911 record without treating legacy babyTEL examples as current compatibility proof.

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Troubleshooting · Cloudli SIP-trunk product, babyTEL rebrand, portal registration, configuration-guide, firewall, capacity, continuity, 911 and terms records reviewed October 25, 2026; Cloudli is the current brand and legacy babyTEL examples remain bounded historical references, while the selected account, region, plan, portal parameters, device guide, network, PBX and current support acceptance govern; no Cloudli or babyTEL account, order, portal, parameter, credential, trunk, registration, NAT mapping, PBX, SBC, firewall, packet, number, call, fax, media stream, continuity event, 911 result, price, availability, compatibility or support response was inspected or tested

Cloudli or babyTEL SIP trunk registration, routing or continuity is wrong

Find the first divergence across current Cloudli identity, legacy babyTEL labels, portal parameters, NAT state, provider continuity, edge receipt, PBX routing and media.

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Provider research · Orange Business Talk product, service-document index, site-management assistance, certified eSBC and ecosystem guides and enterprise-voice material reviewed October 25, 2026; the selected country, order, site, access model, project documents and certified version govern, while the October 25, 2024 Patton guide remains guide-scoped evidence; no Orange account, order, portal, site, trunk, circuit, DNS answer, clock, certificate, SBC, PBX, number, route, packet, call, fax, media stream, failover event, emergency result, price, availability, compatibility or support response was inspected or tested

Orange Business Talk: site, eSBC, routing and media evidence

Qualify the ordered Business Talk or Business Talk IP site, access model, certified eSBC guide, routing policy and media behavior without treating one template as universal service state.

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Troubleshooting · Orange Business Talk product, service-document index, site-management assistance, certified eSBC and ecosystem guides and enterprise-voice material reviewed October 25, 2026; the selected country, order, site, access model, project documents and certified version govern, while the October 25, 2024 Patton guide remains guide-scoped evidence; no Orange account, order, portal, site, trunk, circuit, DNS answer, clock, certificate, SBC, PBX, number, route, packet, call, fax, media stream, failover event, emergency result, price, availability, compatibility or support response was inspected or tested

Orange Business Talk site, trunk, routing or media is wrong

Find the first divergence across ordered site state, portal activation, DNS, time, certificate, eSBC guide, SIP routing and negotiated media.

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Guide · Current branch-23-generated Asterisk FAXSession, FAXSessions and FAXStats actions and response events, FAXStatus, ReceiveFAX, SendFAX, FAXOPT, AMI v2 and network-security documentation were reviewed October 26, 2026; installed Asterisk version, res_fax and technology module availability, manager permissions and filters, session timing, counter lifetime, channel and dialplan ownership, storage, notification and FreePBX behavior remain deployment-specific; no PBX, FreePBX system, module, manager account, credential, fax session, channel, TIFF/F file, notification, packet, media stream or document delivery was inspected or tested

Asterisk AMI fax session inventory and statistics evidence

Use FAXSessions, FAXSession and FAXStats as bounded runtime observations while keeping progress events, terminal application results, negotiated mode and delivered-document evidence separate.

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Troubleshooting · Current branch-23-generated Asterisk FAXSession, FAXSessions and FAXStats actions and response events, FAXStatus, ReceiveFAX, SendFAX, FAXOPT, AMI v2 and network-security documentation were reviewed October 26, 2026; installed Asterisk version, res_fax and technology module availability, manager permissions and filters, session timing, counter lifetime, channel and dialplan ownership, storage, notification and FreePBX behavior remain deployment-specific; no PBX, FreePBX system, module, manager account, credential, fax session, channel, TIFF/F file, notification, packet, media stream or document delivery was inspected or tested

Asterisk AMI fax session is missing, stale or statistics do not match

Find the first divergence across module support, completed active-session inventory, session timing, conditional detail fields, manager delivery, process-counter scope and terminal fax evidence.

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Provider research · Current Optus Wholesale Evolve Voice product, Optus Evolve terms dated November 1, 2025, legal indexes and adjacent-service records were reviewed October 27, 2026. The older Evolve Voice factsheet and SIP Trunking paper are retained only as dated historical context. Public material does not establish which wholesale or enterprise contract applies, the selected application, access, router responsibility, service-delivery point, PBX configuration, features, numbers, capacity, emergency readiness, service level, price, availability or compatibility; the current application, agreement and Optus Technical Description OM.37683 govern. No Optus account, application, quote, order, contract, portal, Evolve IP VPN, MRS, access circuit, NTU, router, firewall, PBX, SBC, credential, number, port, trunk, channel, packet, call, media stream, fax, diversion, outage, emergency outcome, price, availability, compatibility or support response was inspected or tested

Optus Evolve Voice: contract, access, handoff and continuity evidence

Evaluate Optus Evolve Voice without transferring wholesale, enterprise, adjacent-service or historical facts into an uninspected application.

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Troubleshooting · Current Optus Wholesale Evolve Voice product, Optus Evolve terms dated November 1, 2025, legal indexes and adjacent-service records were reviewed October 27, 2026. The older Evolve Voice factsheet and SIP Trunking paper are retained only as dated historical context. Public material does not establish which wholesale or enterprise contract applies, the selected application, access, router responsibility, service-delivery point, PBX configuration, features, numbers, capacity, emergency readiness, service level, price, availability or compatibility; the current application, agreement and Optus Technical Description OM.37683 govern. No Optus account, application, quote, order, contract, portal, Evolve IP VPN, MRS, access circuit, NTU, router, firewall, PBX, SBC, credential, number, port, trunk, channel, packet, call, media stream, fax, diversion, outage, emergency outcome, price, availability, compatibility or support response was inspected or tested

Optus Evolve Voice access, diversion or dual-trunk path fails

Find the first divergence across the governing Evolve Voice agreement, application, access, service-delivery point, PBX, number, signaling, media and selected continuity feature.

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