IP Telephony & SIP Communication Systems · Guangzhou, China
Scenarios · migration and interfaces
Every migration to SIP runs into the same two dozen devices that cannot be replaced: the fax, the lift line, the door entry handset in a storeroom, the alarm line, the phone in the workshop with no network cable near it. A gateway is the box that keeps them working by translating between an analog interface and SIP. This page explains the gateway roles this catalogue documents — the GA10 ATA for a single analog phone, FXS and FXO ports on the PBX itself, paging gateways that drive an existing speaker line, and a radio-over-IP gateway for UHF fleets — and how they are used in a phased migration. NEXVIA designs, manufactures, supplies and commissions the system; the gateways and PBX are manufactured by NEXVIA.
A gateway is chosen by the interface it has to replace, not by port count alone. One analog phone, fax machine or legacy door handset becomes a SIP extension with a GA10 ATA: 2 SIP lines and 1 FXS (RJ11) port, Linux-based, on a 10/100 Mbps port with a Micro USB supply at DC 5 V/1 A. Where the requirement is larger, the analog ports sit on the PBX itself: 4 on the OM20G, up to 12 on the OM50G, up to 48 on the OM80E and up to 96 on the OM200G.
The two directions matter. FXS ports feed analog devices — a phone, a fax, a legacy door entry — with dial tone and ringing; FXO ports take an outside analog line into the system. Keeping two or four FXO ports in the design is what allows an outbound SIP call to fall back to an analog line automatically when the trunk fails, and the published trunk types include a registered-to mode that is documented as a way to extend the PBX FXO ports.
Fax decides several settings at once. Two modes are published, T.38 and G.711 pass-through, with G.711 pass-through required over an analog line and T.38 recommended where the IP platform supports both; the maximum transmission speed stated is 33600 bps, and G.711 pass-through needs G.711U/20 or G.711A/20 selected correctly. Other gateway port counts and host configurations are confirmed on the quotation, because the published materials document the GA10 ATA and the PBX analog ports rather than a full gateway portfolio.
A migration plan that counts desk phones and forgets the fax, the lift line, the alarm line and the door handset in the plant room will fail at cut-over. Walk the site with a list of line and handset positions before the analog port count is fixed.
Fax is the classic migration casualty: T.38 and G.711 pass-through behave differently, G.711 pass-through is required over an analog line, and both sides have to agree. Set G.711U/20 or G.711A/20 correctly, use a DID for the fax extension, and test with real documents before handover.
An ATA solves one position; it does not solve a floor of them. The design question is whether the requirement is best met by PBX analog ports, a gateway, a converter over existing cable, or replacing the device — and the answer differs per position.
A gateway introduces a second device into the call path, with its own power and its own firmware. Document which positions depend on it, put the power supply on the critical circuit where the position matters, and include it in the maintenance schedule rather than only in the commissioning file.
| Size band | System | Devices | Notes |
|---|---|---|---|
| One or two analog devices — a fax and a door handset | GA10 ATA gateway (2 SIP lines, 1 FXS port), registered to any OM model | 1 analog phone or fax on the FXS (RJ11) port, with the PBX holding the dial plan and the trunks | The GA10 is a desktop or wall-mounted unit powered from Micro USB at DC 5 V/1 A, with status LEDs for the FXS port, the network, SIP registration and power. It supports three-way voice conference and remote-office access over the internet. |
| Small office keeping 2 to 4 analog lines | OM20G — 24 SIP trunks; 4 analog ports as 4 FXS, 4 FXO or 2+2 | Analog lines on the FXO ports, a fax or an analog phone on the FXS ports, IP phones on the desk | The sub-model is chosen at order: OM20G-4S, OM20G-4FXO or OM20G-2S/2. The fixed interface card means the port split is decided before purchase rather than at installation. |
| Growing business keeping 6 to 12 analog devices | OM50G — 62 SIP trunks; up to 12 analog ports across 3 interface cards | Mixed FXO and FXS ports by sub-model (6S/6, 8S/4, 10S/2 or 12S), plus IP phones and consoles on the network | Interface cards are 401A-4S and 401A-2S/2, so the port mix is built from the cards as well as the model; the cards connect to a patch panel over Cat5 Ethernet cable. |
| Multi-floor site with a large analog estate | OM80E — 216 SIP trunks; up to 48 analog ports across 13 published sub-models, or OM200G — 496 SIP trunks; up to 96 analog ports | Faxes, analog phones, lift and alarm lines across the frame, with IP telephony on every desk | The OM80E uses 16-line cards with a 4×4 LED status matrix per RJ45; the OM200G uses 4 slots with 24-line cards and supports hot-swap card replacement. |
| Pure SIP site with no analog requirement | OM1000-UC — 1000 SIP trunks; no FXS and no FXO ports | SIP terminals only, with DID/DOD binding up to 4 outside numbers to an extension or group | A site that reaches this model with one analog device left must keep a smaller PBX or a gateway for it, because the OM1000-UC has no analog interfaces at all. |
| Existing paging line or radio fleet to bring across | PA3 or PA2S paging gateways; W712 RoIP gateway for UHF | PA3 and PA2S drive passive speakers and legacy analog horn speakers; the W712 connects one analog or DMR II radio per channel | Both are gateways in the same architectural sense as an ATA: they translate an existing non-SIP asset onto the platform. Available models and port counts beyond those documented are confirmed on the quotation. |
| Item | What it connects | Published capability | Notes |
|---|---|---|---|
| GA10 ATA gateway | One analog phone or fax machine to SIP | Linux, 2 SIP lines, 1 FXS (RJ11) port, 3-way voice conference, DTMF In-band/RFC2833/SIP Info, caller-ID Bellcore/ETSI/NTT/DTMF, 10/100 Mbps single port | Codecs G.722, Opus, G.711A/U, G.729A/B, G.726 and iLBC; 0–45 °C, 10–95% RH; desktop or wall-mounted, powered by Micro USB DC 5 V/1 A; status LEDs for FXS, network, SIP registration and power |
| OM20G analog ports | Up to 4 analog devices or lines | 4 ports total: 4 FXS, 4 FXO or 2 FXS + 2 FXO by sub-model, on a single interface card | Part of the PBX rather than a separate box; ring groups hold up to 40 extensions on this model |
| OM50G analog ports | Up to 12 analog devices or lines | Published sub-models provide 6 FXS/6 FXO, 8 FXS/4 FXO, 10 FXS/2 FXO or 12 FXS, across up to 3 interface cards | Interface cards are 401A-4S and 401A-2S/2, terminated on a patch panel over Cat5 Ethernet cable |
| OM80E analog ports | Up to 48 analog devices or lines | 13 published sub-models from 8 FXS/8 FXO to 48 FXS or 48 FXO, on 16-line interface cards | Each card carries a 4×4 LED status matrix per RJ45; remote recording only on this model |
| OM200G analog ports | Up to 96 analog devices or lines | 4 slots with 24-line cards: 24FXS, 24FXO, 16FXS+8FXO or 12FXS+12FXO; cards can be replaced while the unit is running | PT2400 or PT4800 lightning-protection patch panels are the published accessories |
| OM1000-UC analog ports | None — SIP only | 0 FXS and 0 FXO ports; DID/DOD binds up to 4 outside numbers to an extension or group | A surviving analog device needs a gateway or a smaller PBX in the design |
| PA2S paging gateway | An existing passive speaker or amplifier line | 10–30 W mono output adapting to the input voltage, line out for an external active speaker, SOS call key, 1 short-circuit in and 1 out with a built-in relay, recording output | PoE to IEEE 802.3af or 12–24 V 2 A DC; −30 °C to 60 °C |
| PA3 paging gateway | An existing paging system with scheduled audio and camera linkage | 10–30 W mono output, line out, SOS call key, line in 3.5 mm, USB 2.0 and TF card, analog output to passive speakers or amplifiers, video linkage with an IP camera | PoE / PoE+ (IEEE 802.3at, published as PoE Class 4) or 12–24 V 2 A DC; −20 °C to 50 °C |
| W712 RoIP gateway | One UHF radio channel to SIP | UHF 400–470 MHz radio module; one analog or DMR II radio plus one SIP call; group calls between radios and SIP phones; recording to a TF card up to 128 GB or USB | SIP standard protocol; web deployment and management; trans-regional communication using DSS speed-dial keys |
| SIP trunk types on the PBX | The provider side of the migration | Direct-IP, registered and registered-to types, with multi-platform registration, IMS interconnection and a backup SIP server by fixed address or DNS SRV | The registered-to type is documented as a way to extend the FXO ports of the OM; local port default 5060 and registration timeout range 15–86400 with a default of 600 |
| Requirement | Keeping a separate analog system alive | This IP design | What changes operationally |
|---|---|---|---|
| Analog phones and fax | A second exchange, a separate pair per device and a separate fault routine | FXS ports on the PBX (4, 12, 48 or 96 by model) or a GA10 ATA for a single position, all registering on one platform | One dial plan, one records feed, one maintenance routine |
| Outside analog lines | Kept on the old exchange, disconnected from the rest of the site | FXO ports on the PBX, with automatic outbound fallback to an analog line when the SIP trunk fails | The old lines become the continuity path rather than a parallel system |
| Fax | A dedicated fax line and machine | T.38 or G.711 pass-through, with G.711 pass-through required over an analog line; a DID number is recommended for the fax extension | Fax travels the same infrastructure, with the settings documented rather than guessed |
| A position with no network cable | A pair back to the old exchange | An FXS port where the pair still reaches the frame, a GA10 over the network, or a PN1 converter putting network and power on the two-core pair | The position is reached without depending on the old exchange |
| Paging and speakers | A separate amplifier with its own timetable | PA3 and PA2S gateways drive the existing passive speakers with a 10–30 W mono output and a line out for the amplifier | The old speaker line becomes a zone on the new system |
| Radios | A radio network with no connection to the telephone | The W712 puts one UHF channel on the system with group calls between radios and SIP phones and recording of both | One talk group spans the radio fleet and the phones |
| Remote and branch sites | A second exchange or nothing | SIP extensions register over the internet and multi-site networking shares extension numbers and trunk capacity across PBXs | A branch joins the numbering plan rather than duplicating it |
| Area | Device | Note |
|---|---|---|
| Single analog phone or fax | GA10 ATA gateway | Linux-based with 2 SIP lines and 1 FXS (RJ11) port, 3-way voice conference, DTMF In-band/RFC2833 and SIP Info, caller-ID Bellcore/ETSI/NTT/DTMF and codecs G.722, Opus, G.711A/U, G.729A/B, G.726 and iLBC; desktop or wall-mounted, powered by Micro USB at DC 5 V/1 A, on a 10/100 Mbps port. |
| Analog lines from the provider | FXO ports on the PBX (4 / 12 / 48 / 96 by model) | FXO ports take the existing exchange lines and allow automatic outbound fallback to an analog line when a SIP trunk fails. Ordered as FXS, FXO or a mix, and terminated on a patch panel over Cat5 Ethernet cable. |
| Analog phones, fax and legacy handsets | FXS ports on the PBX, or a GA10 where the device sits away from the frame | Fax runs as T.38 or G.711 pass-through at a maximum transmission speed of 33600 bps, with a DID number recommended for the fax extension. Never connect a live analog trunk or extension line to an FXS port. |
| Existing paging amplifier and speaker line | PA2S or PA3 SIP paging gateway | Both publish a 10–30 W mono output that adapts to the input voltage and a line out for an external active speaker or amplifier; PA2S carries an SOS call key, 1 short-circuit in and 1 out with a built-in relay; PA3 adds line in, USB 2.0, TF storage and camera linkage. |
| UHF radio fleet | W712 RoIP gateway | Integrates a UHF 400–470 MHz radio module and supports one analog or DMR II radio plus one SIP call, with group calls between radios and SIP phones and recording to a TF card up to 128 GB or USB storage. |
| Positions with no usable network cable | PN1 converter, or PN8 / PN24 2-wire switch | PN1 carries network and power over an existing two-core pair up to 1600 m for the network function without power, at AC 100–240 V; PN8 and PN24 distribute up to 8 and up to 24 devices at up to 300 m for network plus power. |
| The SIP side of the interface | SIP trunks from the provider, with a backup SIP server | Trunk types published as direct-IP, registered and registered-to, with multi-platform registration and IMS interconnection. A backup server can be configured by fixed address or DNS SRV, with the main server monitored by periodic OPTION requests. |
It translates between an interface a SIP platform does not have and one it does. An ATA gateway gives an analog telephone a SIP account; an FXO port brings an outside analog line into the PBX; an FXS port gives an analog phone, fax or legacy handset a dial tone from the PBX; a paging gateway drives a passive speaker line; a radio gateway joins a UHF channel to the system.
FXS is the port that behaves like an exchange: it supplies dial tone and ringing to an analog device. FXO is the port that behaves like an analog telephone: it receives an outside analog line. In practice, FXS keeps analog instruments and FXO keeps analog lines.
Yes, on an FXS port. Fax runs two ways on this platform: T.38 and G.711 pass-through, with G.711 pass-through required over an analog line and a maximum transmission speed of 33600 bps.
Three documented routes. Where the pair still reaches the equipment room, the position can stay on an FXS port; where the device can move, a GA10 ATA gives it a SIP account over the network; and where only two-core cable exists at the wall, the PN1 converter carries network and power over that pair.
Yes, where FXO ports are fitted: an outbound SIP call can be set to fall back to an analog line automatically when the trunk fails. That is one of the reasons a migration often keeps two or four copper lines in place.
Yes, and they are documented as the same architectural idea applied to other assets. PA3 and PA2S are SIP paging gateways with a 10–30 W mono output and a line out for an external amplifier, and the W712 is a radio-over-IP gateway with a UHF 400–470 MHz module and one analog or DMR II channel.
Any model except the OM1000-UC, which has no FXS and no FXO ports at all. The published analog capacity is 4 ports on the OM20G, up to 12 on the OM50G, up to 48 on the OM80E and up to 96 on the OM200G.
Gateway roles, and where each is documented
| Role | What it translates | Published equipment | Typical use |
|---|---|---|---|
| Analog telephone adapter | A single analog phone or fax to SIP | GA10: 2 SIP lines, 1 FXS (RJ11) port, Linux, 10/100 Mbps port | One position left over from an old system |
| Analog extension and line ports | Analog devices and provider lines on the PBX itself | 4 / 12 / 48 / 96 ports on the OM20G / OM50G / OM80E / OM200G, FXS, FXO or a mix | A phased migration with the copper still in service |
| Paging gateway | An existing amplifier and speaker line to SIP paging | PA3 and PA2S: 10–30 W mono output, line out, SOS call key, built-in relay on PA2S | A building that keeps its old paging installation |
| Radio-over-IP gateway | A UHF radio channel to SIP calls and talk groups | W712: UHF 400–470 MHz module, one analog or DMR II radio plus one SIP call | A plant with a radio fleet that must not be replaced |
All four register with the same PBX and the same dial plan. That is the point of the architecture: the gateway is an interface, not a second system.
An FXO port connects customer equipment to a line that belongs to a provider, and the terms of that connection — what may be attached, what signalling and tones are used, how many lines a site may take and what happens on an emergency call — are governed by the provider and by national telecom rules, which differ by country. The published material behind this page records no approval or certification for these products. A compliant design is one where the organisation has confirmed with its own line provider and adviser what may be connected and on what terms, before the analog port mix is ordered.
Fax on T.38 or G.711 pass-through, alarm signalling over an analog line and legacy door-entry or lift lines are the devices that most often hold up a migration, because each has its own requirement about how the line behaves. The published settings — G.711 pass-through required over an analog line, a maximum transmission speed of 33600 bps, a recommended DID number for the fax extension and the option to allow the far end to switch to T.38 — are the technical answers. Whether an alarm or lift line may be moved onto a gateway at all is a question for the alarm or lift contractor and the applicable code, and it needs answering before the line is touched.
Analog ports need a patch panel: interface cards connect to it over Cat5 Ethernet cable, the FXO and FXS groups on the RJ45 connectors are broken out into pairs, and the published accessories for this are the PT2400 and PT4800 lightning-protection panels. The PBX chassis is earthed as the installation diagram shows. The instruction printed with the interface cards is explicit, and is worth repeating: never connect a live analog trunk line or an exchange extension line to an FXS port, because it will damage the port. Cable classes, separation and protection requirements are local; confirm them with the site own contractor before the frame is rebuilt.
This page makes no certification claim: the published material records no third-party safety certification for these products, and no type-approval or regulatory position for any country. It also documents a specific gateway portfolio — the GA10 ATA, the analog ports on the OM models and the PA3, PA2S and W712 gateways — rather than every possible interface. Where a project needs a port count or an interface that is not in those documents, the model and its published figures are confirmed on the quotation instead of being inferred from this page.
We have not published a named reference project on this page. The site does not carry customer names or installation records until the client confirms in writing which projects may be made public.
Page author: NEXVIA EngineeringPublished:Last updated:
Covers: voip gateway · fxs gateway · fxo gateway · sip gateway · analog telephone adapter
All IP telephony, intercom and paging equipment in this design is supplied and integrated by NEXVIA.
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