Scenarios · retrofit cabling

2-Wire IP Phones — network and power over the two cores already in the wall

A 2-wire IP phone is not a phone with a smaller connector: it is a phone or device that receives both its network connection and its power over two copper cores, which is the cable a hotel, a hospital or a period building already has inside it. The technique comes from the 2-wire product family in this catalogue — a converter for a single point and two 2-wire switches for a floor — and it is the documented answer to the refurbishment that cannot open the walls. This page sets out what the technique carries, what the published distance limits are, and how the 2-wire telephone models themselves fit into the plan. NEXVIA designs, manufactures, supplies and commissions the system; the converters, switches and handsets are manufactured by NEXVIA.

Network and power travel over the two cores already in the wall, so the riser does not have to be opened
PN1 for a single point: up to 1600 m for the network function without power, with a local AC 100–240 V supply
PN8 and PN24 for a floor: up to 8 and up to 24 two-wire devices at a maximum connection distance of 300 m for network plus power
Two 2-wire telephones are published in the range: the X303-2 Wire with a 2.4-inch colour screen and the H1-2 Wire with 8 programmable service keys
The technique covers more than phones: door phones, indoor units, care stations and speakers can sit on the same pair
It is the labelled retrofit route in the residential material — a historical building solution with no new wiring required

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Two-wire converter that carries network and power over an existing two-core cable

The short answer

The 2-wire technique solves one problem: a building where the only cable that exists is a two-core pair. Instead of running data cable to every position, a converter or switch places the network signal and the power onto that pair. A single position is served by the PN1, which reaches up to 1600 m for the network function without power and is supplied locally at AC 100–240 V; a floor is served by the PN8 (up to 8 two-wire devices) or the PN24 (up to 24 devices), both rated to a maximum connection distance of 300 m for network plus power with a built-in AC 100–240 V supply.

Two things decide the design: distance and power. The distance figures are published per device rather than as a single rule — 1600 m for the network function without power on PN1, 300 m for network plus power on PN8 and PN24 — so the survey has to record both the run length and the number of devices at the far end. Power is the second: PN1 takes its supply locally, PN8 and PN24 have built-in supplies, and PN24 is a standard 1U chassis for a riser or equipment cabinet.

The handsets themselves are published models, not adaptors bolted to ordinary phones: the X303-2 Wire is a 2.4-inch colour-screen phone that takes power and network from the 2-wire supply, and the H1-2 Wire is a service handset with 8 programmable keys, G.722 and Opus audio and faceplate customisation. Prices are not published on this site — every retrofit is quoted per point count, device mix and the measured condition of the existing pairs.

Two-core topology: network and power carried over the cabling already in the wall

What goes wrong on this type of site

The pair is doing two jobs at once

A 2-wire run carries signal and power together, so distance, device count and pair condition all interact. The published figures give the envelope; the survey gives the answer per position.

The device list is narrower

The 2-wire family publishes specific handsets — the X303-2 Wire and the H1-2 Wire — plus the door, care and speaker devices that use the same technique. Match the position to the published list rather than adapting a general-purpose phone.

Power arrives locally, not from the cabinet

PN1 needs an AC 100–240 V supply at the position, while PN8 and PN24 have their own supplies and PN24 is a 1U chassis. The electrical design has to reach the same points as the cabling design.

A mixed building is the normal case

New cable where the walls are open, converters on the pairs that remain, analog devices on FXS ports during a phased changeover: a retrofit is rarely uniform, and the model should be planned on the finished requirement rather than the first phase.

Choosing by size

Size band	System	Devices	Notes
A single position on a pair — one room, one door, one handset	Any OM model, with a PN1 converter at the position	1 two-wire device: a 2-wire IP phone (X303-2 Wire / H1-2 Wire), a door phone, an indoor unit or a care station	PN1 carries network and power over the existing two-core cable, up to 1600 m for the network function without power, with a local AC 100–240 V supply. The 1600 m figure applies to the network function without power, so a powered device needs a shorter run.
A floor or a riser section — up to 8 points	OM20G or OM50G — 24 or 62 SIP trunks	Up to 8 two-wire devices on a PN8, fed from the PBX switch through the existing riser	The PN8 cascades over Ethernet cable, has a built-in power supply at AC 100–240 V, and is rated to a maximum connection distance of 300 m for network plus power.
A large floor, wing or multi-floor riser — up to 24 points	OM50G or OM200G — 62 or 496 SIP trunks	Up to 24 two-wire devices on a PN24 in a standard 1U chassis, with PN1 converters for isolated points beyond it	PN24 has the same 300 m limit for network plus power and a built-in AC 100–240 V supply, and its 1U form factor suits a riser cabinet or a communal equipment room.
Hotel or apartment refurbishment on the existing riser	OM50G — 62 SIP trunks; up to 12 analog ports where pairs still reach the frame	Room handsets and door stations at the existing points, with PN converters per floor and per isolated position	The residential material labels this the historical-building retrofit case, described as needing no new wiring. Rooms that can take a data run should still take one; the 2-wire route is for the positions that cannot.
Mixed building — part new cable, part existing pair	OM200G — 496 SIP trunks; up to 96 analog ports on 24-line interface cards	New IP devices on data cabling where the walls are open, PN converters on the pairs that remain, analog extensions on FXS ports during a phased changeover	A mixed route per floor is the normal outcome of a refurbishment. Plan the model on the requirement at the end of the project rather than on the wiring of the first floor converted.
Greenfield installation where data cabling is planned anyway	OM20G to OM1000-UC — 24 to 1000 SIP trunks	Standard PoE IP phones on data cable, with the 2-wire devices used only where a pair is genuinely the only option	The 2-wire technique is a retrofit tool, and it is quoted per position. Where a new data run is possible, PoE on the published models is usually the simpler design.

Numbers behind the design

The 2-wire family, as published
Model	What it is	Published capability	Distance, power and notes
PN1	2-wire converter for a single point	Extends network and power over an existing two-core pair to the device at the far end	Up to 1600 m for the network function without power; external power AC 100–240 V; the image label in the solution brochure ties it to historical building retrofit
PN8	2-wire PoE switch for up to 8 devices	Network plus power over 2-wire, switchable; cascading via Ethernet cable; up to 8 two-wire devices	Maximum connection distance 300 m for network plus power; built-in power supply AC 100–240 V
PN24	2-wire PoE switch for up to 24 devices	Network plus power over 2-wire, switchable; up to 24 two-wire devices	Maximum connection distance 300 m for network plus power; built-in power AC 100–240 V; standard 1U chassis
X303-2 Wire	2-wire IP phone	Colour-screen desk phone in the X300 series with 2-wire power and network supply	2.4-inch colour screen; the material states the 2-wire supply rather than a PoE class, so the position power is confirmed with the converter or switch design
H1-2 Wire	2-wire service handset, hotel and guest-room use	8 programmable service keys with speed-dial functions, G.722 and Opus wideband audio, faceplate customisation	Supports 2-wire power and network supply; the entry handset of the H series in 2-wire form
PoE IP phones (for comparison)	The same roles on a data network	Integrated PoE is published on models such as the H2U, H3W, H4W, H5W and H6W, and on most V and X desk phones	One network run per position; the option wherever a data cable can be installed

This design against pulling new cable
Requirement	Pulling new network cable	This 2-wire design	What changes operationally
The riser	Open the riser, pull data cable to every floor and every room, make good the finishes	The existing pair carries network and power; PN8 or PN24 distributes a floor and PN1 covers isolated points	The building keeps its finishes, and the work is shorter
The position	One data outlet plus a PoE port on a switch	One converter or one 2-wire switch port, with the published distance limits applied	A position is a port on the converter rather than a switch port
Distance	The usual 100 m Ethernet limit to the outlet, and less with patch cords	PN1 reaches up to 1600 m for the network function without power; PN8 and PN24 reach 300 m for network plus power	Long risers and outbuildings become reachable without an intermediate switch
Power	The switch provides PoE up to its budget	PN1 takes a local AC 100–240 V supply; PN8 and PN24 have built-in supplies at AC 100–240 V	Power is provisioned at the converter or the floor switch rather than at the cabinet
The devices	Any PoE SIP terminal	2-wire devices — the X303-2 Wire and H1-2 Wire handsets — and door phones, indoor units, care stations and speakers on the same pair	The phone model list is narrower, so the design is confirmed per position
Change of use later	A new outlet and a switch port	A port on the converter or a new converter at the position	Room changes stay cheap as long as a pair reaches the position
Risk to manage	Cable damage in the riser	Pair condition, distance and device count all matter, because the pair is carrying both signal and power	Measure and record every reused pair at survey, and keep the record with the as-built drawings

Deployment by area

Area	Device	Note
A single position with only a pair available	PN1 2-wire converter	Carries network and power over an existing two-core cable, reaching up to 1600 m for the network function without power, with a local supply at AC 100–240 V. The solution material labels it for historical building retrofit.
A floor or wing with up to 8 points	PN8 2-wire PoE switch	Network plus power over 2-wire for up to 8 two-wire devices, cascading over Ethernet cable, with a built-in power supply at AC 100–240 V and a maximum connection distance of 300 m for network plus power.
A large floor or multi-floor riser with up to 24 points	PN24 2-wire PoE switch	Up to 24 two-wire devices on the same 300 m network-plus-power limit, with a built-in supply at AC 100–240 V in a standard 1U chassis for a riser or equipment cabinet.
Desk or back-office position on a pair	X303-2 Wire	Colour-screen desk phone with a 2.4-inch display that takes 2-wire power and network supply; the X300 series build in 2-wire form.
Guest room or service position on a pair	H1-2 Wire	8 programmable service keys with speed-dial functions, G.722 and Opus wideband audio and faceplate customisation, with 2-wire power and network supply.
Door, room or ward position on a pair	Door phones, indoor units and care stations fed from the same pair	The same technique is used for entrance stations, indoor units and care stations, which is what makes a whole-building retrofit possible rather than a single telephone position. Confirm the device and its power at each point on the quotation.
Positions that can take a data run	PoE SIP phones and speakers on standard cable	Integrated PoE is published on the H2U, H3W, H4W, H5W and H6W hotel handsets and on most V and X desk phones, with the SIP speaker family on PoE as published — the simpler route wherever a network cable can be installed.

Questions buyers ask

What is a 2-wire IP phone?

It is a telephone that receives its network connection and its power over two copper cores, instead of over a standard four-pair network cable with PoE. The range includes the X303-2 Wire, a colour-screen desk phone with a 2.4-inch display, and the H1-2 Wire, a service handset with 8 programmable keys and G.722 and Opus audio.

The phone itself is a SIP terminal; what changes is how it is connected, and that is what makes an old riser usable.
The technique is delivered by the PN1 converter for a single point, or the PN8 and PN24 switches for 8 and 24 devices on a floor.
The 2-wire category is the material own product grouping, so the switching and the handsets are designed as one family.

How far can a 2-wire run go?

It depends on the device, and the published figures are specific: PN1 reaches up to 1600 m for the network function without power, while PN8 and PN24 are rated to a maximum connection distance of 300 m for network plus power.

The 1600 m figure applies to the network function without power; a powered device needs a shorter run, which is why the survey records distance and device type together.
The 300 m figure covers network plus power, which is the case a floor distribution point is normally designed for.
Two-wire points that are close together should not be assumed to behave like a data network: the pair is carrying power as well as signal.

How many devices can one 2-wire switch carry?

The PN8 carries up to 8 two-wire devices and the PN24 up to 24. Both have a built-in power supply at AC 100–240 V and the same 300 m limit for network plus power, and the PN8 can be cascaded over Ethernet cable while the PN24 is a standard 1U chassis.

A wing with 8 rooms suits a PN8; a full floor or a larger wing suits a PN24 in a riser cabinet.
A single isolated position beyond the reach of a floor switch takes its own PN1 rather than a longer run from the switch.
Confirm the device count and its power draw against the published figures, and confirm the final layout on the quotation.

Which devices can sit on the two cores?

More than telephones. The 2-wire family is documented as carrying network and power to the devices at the far end, and this catalogue uses the same technique for door phones, indoor units, care stations and speakers — which is what makes a whole retrofit possible rather than just a telephone position.

The H1-2 Wire is the guest-room or service handset; the X303-2 Wire is the desk phone of the family.
The same pair technique appears in the residential material as the historical-building retrofit, and in the elevator scenario as the travel-cable route.
Where a position can take a standard PoE device, the wider model range — the H series hotel handsets, V and X desk phones, and the SIP speaker family — is available on data cable.

Why not just pull new cable?

Sometimes you should, and the design says so: where a wall is open, a data run with a PoE device is the simpler and more flexible solution. The 2-wire route exists for the positions where opening the building is not possible — stone walls, heritage finishes, occupied hotel floors and long risers.

A mixed route per floor is normal: new cable where the builder is already working, converters on the pairs that remain.
The 2-wire technique also reaches further than Ethernet, with PN1 published at up to 1600 m for the network function without power, which suits outbuildings.
The trade-off is a narrower device list and a more careful survey, because pair condition and power now matter for every position.

What should the survey record?

Four things per position: the pair count and condition, the run length, the device that has to sit at the far end, and whether power is available locally. Those four answers decide between a PN1, a PN8 or PN24 port, a new cable run and, in some cases, leaving the position on an analog FXS port.

Pair continuity and insulation decide whether the pair can be reused at all; age is not the test.
Distance decides the device: PN1 up to 1600 m for the network function without power, PN8 and PN24 up to 300 m for network plus power.
Every reused pair should be labelled at both ends and recorded on the as-built drawing, together with the converter or switch port it feeds.

Can a 2-wire phone be added later?

Yes, wherever a pair reaches and a converter or switch port is available. That is the point of designing the distribution this way: a new position is a port on the floor switch or a new PN1 at the point, rather than a new riser cable.

Leave spare ports on the PN8 or PN24 at design stage, because the cost of a spare port is far lower than the cost of opening a finished floor.
Whether the extra device needs a converter of its own depends on the published distance limit at that position.
The dial plan does not change with the cabling method: a 2-wire phone is a SIP extension like any other.

Cabling, power and network notes

PN1 carries network and power over an existing two-core cable, up to 1600 m for the network function without power, and is supplied locally at AC 100–240 V; the power distinction is part of the distance budget.
PN8 and PN24 carry network plus power to up to 8 and up to 24 two-wire devices, with a maximum connection distance of 300 m and built-in power supplies at AC 100–240 V; PN24 is a standard 1U chassis for a riser or cabinet.
The PN8 can cascade over Ethernet cable, which is how one distribution point serves a wing without a second uplink.
Record pair count, continuity, run length and device count per position at survey; those four figures decide between a converter, a switch port and a new cable run.
Label both ends of every reused pair and keep the converter and switch port list with the as-built drawings, because a 2-wire position that is not recorded becomes an unknown pair in the next refurbishment.
Where a position cannot be reached by a pair, the documented alternatives are a wireless device (Wi-Fi 6 handsets or 433 MHz care buttons) or an analog extension on an FXS port — up to 12 ports on the OM50G and up to 96 on the OM200G.
Keep signal and power separation rules in mind where the reused pair runs alongside mains, and confirm the local wiring requirements with the site own contractor before the riser is closed.

What the two cores carry

The 2-wire route, point by point

Element	Published figure or fact	What it decides
Cable	An existing two-core pair in the riser or the wall	Whether a position can be reached without new cabling at all
Signal and power	Carried together over the pair to the device at the far end	That the pair is doing two jobs, so distance and load both matter
PN1 single point	Up to 1600 m for the network function without power; external AC 100–240 V	Isolated positions, outbuildings and heritage rooms
PN8 distribution	Up to 8 two-wire devices; 300 m for network plus power; built-in AC 100–240 V; cascades over Ethernet cable	A wing or a small floor
PN24 distribution	Up to 24 two-wire devices; 300 m for network plus power; built-in AC 100–240 V; 1U chassis	A full floor or a larger wing, in a riser cabinet
Handsets	X303-2 Wire (2.4-inch colour screen) and H1-2 Wire (8 programmable service keys, G.722 and Opus)	The phone on the desk in a 2-wire design
Other devices	Door phones, indoor units, care stations and speakers on the same technique	The scope of a retrofit beyond telephony

The 1600 m figure is published for the network function without power, and 300 m for network plus power — read the two together before choosing a route for a powered device.

Where the technique fits, and where it does not

It fits occupied buildings: hotel floors, hospitals, schools and offices where the riser cannot be opened and the finishes are protected.
It fits heritage and stone-walled buildings, which is why the residential material uses the historical-building retrofit as the labelled case.
It fits long runs to outbuildings, because PN1 is published at up to 1600 m for the network function without power — further than a standard Ethernet run.
It fits mixed buildings when combined with new cable on the floors that are already open and analog FXS ports for the devices that stay analog for a while.
It does not fit a position with no pair, a damaged pair, or a load that exceeds the published device count and distance — in those cases the design has to change, not the claim.

Running a 2-wire installation after handover

Keep a port schedule for every PN8 and PN24 and a converter list for every PN1 position; the schedule is what makes the next change cheap.
Extensions work the same way as on any SIP system: numbers from 200 upwards, created in batches, with the phones provisioned centrally.
A converter is a device in the call path, so include it in the maintenance schedule and in the fault-finding routine for the positions it serves.
Where a floor is later re-cabled, the 2-wire devices can be replaced with PoE models and the converter recovered for another position — the technique is not a one-way decision.
Record which positions are on a pair because of heritage or occupancy constraints, so a future project does not reopen a decision that was made deliberately.

Compliance, standards and local requirements

Reusing building cable: measure, record and be honest about the limit

A two-core pair that carries network and power is being used outside its original purpose, so the design case rests on measurement rather than assumption: pair count, continuity, insulation, run length and the number of devices at the far end. The published figures are PN1 at up to 1600 m for the network function without power, and PN8 and PN24 at a maximum connection distance of 300 m for network plus power. Local wiring rules on separation from mains, containment, earthing and the reuse of existing cabling apply, and they differ by country — confirm them with the site own contractor, and record every reused pair on the as-built drawing so the next alteration is not a guess.

Power arrangements at the converter

The 2-wire parts of the system have their own supply requirements: PN1 takes a local AC 100–240 V supply at the position, while PN8 and PN24 have built-in supplies at AC 100–240 V and PN24 mounts in a standard 1U chassis. That means a riser cabinet or a nearby socket is part of the design, and the person specifying the installation should know which points need a supply and which do not. Whether a local supply is acceptable in a particular riser, and how it is protected, are local electrical matters to be confirmed with the site own electrical contractor.

Fire, life-safety and the positions that must not depend on a converter

Where a two-core route is used for a lift intercom, a care call point or an emergency call station, the communication chain may be subject to a code that says how it must remain available — including what happens when a normal supply fails. A converter in that chain is a dependency, and the design has to say so. The published material records no certification and this page makes no conformity claim; the arrangement for any emergency position must be confirmed with the lift, fire or care adviser and the local code authority before the equipment is ordered.

If a position cannot be reached, say so instead of stretching the design

The honest limit of this technique is where a pair does not exist, is damaged, or is too long for the device count at the far end. In those cases the options are a new cable run, a wireless device where the model supports one — such as the Wi-Fi 6 hotel handsets or the 433 MHz care buttons — or leaving the position on an analog FXS port during a phased changeover. Writing that decision down per position, rather than promising that every position can be converted, is what keeps a retrofit project deliverable.

Standards referenced

Frequently asked questions

How far can it reach?

PN1 reaches up to 1600 m for the network function without power, and PN8 and PN24 are rated to a maximum connection distance of 300 m for network plus power. Read the two figures together before designing a powered position.

Does it need new cabling?

No — the technique exists to use the cable already in the building. It is the labelled historical-building retrofit route in the residential material, described as a solution with no new wiring required.

Can doors, care points and speakers use the same pair?

Yes. The same 2-wire technique is documented for entrance stations, indoor units, care stations and speakers as well as telephones, which is what allows a whole building to be converted over its existing pairs.

What if a position has no pair at all?

Then the options are a new data run with a PoE device, a wireless device where the model supports one (Wi-Fi 6 handsets, or the 433 MHz care buttons), or an analog extension on an FXS port during a phased changeover — up to 12 ports on the OM50G and up to 96 on the OM200G.

How is the 2-wire equipment powered?

PN1 takes a local supply at AC 100–240 V; PN8 and PN24 have built-in power supplies at AC 100–240 V. The devices at the far end take their power from the pair, which is why the distance and device count limits matter.

Project evidence

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:2026-09-29Last updated:2026-10-13

Covers: 2 wire ip phone · two wire intercom · 2 wire intercom system · hotel retrofit wiring · ip phone over existing cabling

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