Quick answer: "PSTN switch-off" is the regulator-backed retirement of the public switched telephone network — the copper access lines that carried analogue voice for a century — replaced by IP-only voice service. Incumbents in the UK and across the EU are running this on announced national timelines, and the UK's own programme is well past its announced milestones, so treat every published date as a moving target your carrier confirms in writing. The demand it places on a tenant is the same everywhere: move voice onto SIP trunks before the copper line underneath them is cut, decide whether to keep the carrier relationship (BYO) or port the numbers to the platform, and run the migration as a checklist you own — not a project a vendor does for you.
This is an industry-news explainer in the same family as the 10DLC sanction sweep and the A2P carrier-fee roundup — external regulatory movement every voice buyer sits under, plus the tenant-owned posture for meeting it. Nothing described here is an Orbit product change; the hooks at the end point at shipped SIP-trunking and porting controls.
What the PSTN switch-off is, and the regulatory calendar
The PSTN is the circuit-switched access network: the copper pair from the exchange to your building, the analogue or ISDN line on top of it, and the TDM switching behind that. "Switch-off" means the incumbent operates an IP-only access network, so every service that rode the copper line — voice lines, PBX trunks, fax, alarm circuits, lift phones, EPOS terminals — has to move to an IP bearer before the published cut-off.
The calendar is genuinely regulatory, not marketing:
- United Kingdom. Openreach's copper-retirement programme is regulator-blessed (Ofcom) and nationally coordinated; the industry direction is that analogue and ISDN services withdrew from sale long ago and the national stop-sell/cut-over milestones are already behind us, with individual exchange areas announced for withdrawal on rolling notices. The lesson buyers should take from the UK is that published dates move — the announced nationwide milestone slipped from its original target, and the programme now proceeds exchange-by-exchange. Your incumbent's written notice for your lines is the calendar that matters.
- European Union. There is no single EU-wide cut-off date. Each national regulator (and each incumbent) sets its own copper-switch-off timetable; several member states have completed or substantially completed theirs, others stagger by region. If you operate lines in more than one member state, you hold more than one calendar.
- Everywhere else. The same pattern — copper retirement announced in tranches, dates moving as take-up lags — is playing out across other markets. The constant is that the access medium dies first and the commercial product wrapped around it dies later; waiting for the product notice is waiting until the expensive options are gone.
The tenant-owned posture is simple: treat the published date as an upper bound, get your carrier's written exchange-level notice, and budget the migration against the earliest plausible cut-over, not the headline date.
What copper retirement demands of a tenant
Copper retirement removes the bearer, not the numbers. That distinction decides the whole migration shape, and it splits into two tenant-owned decisions.
Decision 1 — who carries the PSTN-facing relation after the move. Once the access is IP, someone terminates your calls with a carrier. As the SIP trunking and BYO carrier guide lays out, you either keep your incumbent carrier relationship and point a SIP trunk at the platform (BYO carrier — your negotiated rates, your numbers stay registered where they are), or you port the numbers onto the platform's carrier and let it handle PSTN end to end. Copper retirement forces this decision for every copper-fed line you own; a tenant that defers it is really choosing the incumbent's managed-conversion path, which is the one option nobody priced.
Decision 2 — what happens to everything that was not a desk phone. The lines that miss the headline migration are the ones nobody filed as "telephony": alarm signalling, lift and emergency phones, fax machines, door-entry systems, payment terminals. Each needs an IP path or a decommissioning decision, and each is tenant-owned — no platform audits your building for you.
Two hard constraints follow from both decisions:
- Outbound termination still goes through the platform's own switch. On Orbit, outbound PSTN egress runs over Devotel's wholesale softswitch regardless of which posture you pick; a BYO trunk is an inbound-delivery and carrier-preservation device, not an alternate egress route.
- Numbering is the long pole. A port takes weeks end to end and the losing carrier's review clock only starts once the paperwork is clean. Starting porting after the cut-over notice lands is discovering the critical path at the worst time.
What Orbit ships today for the migration
The platform pieces below are shipped surfaces, not roadmap items — the same ones the SIP/BYO and porting guides document end to end:
- SIP trunking with BYO carrier. Orbit ingests your existing carrier's trunk per trunk — digest authentication or IP allowlist, credentials encrypted at rest, per-attempt auth logging, and a failover chain that walks to your configured secondary when the primary is unregistered. Your carrier stays your carrier; the call lands on the same routing, IVR, and agent path as platform-carrier traffic. The SIP trunking and BYO carrier guide covers the tradeoffs and the ingestion model.
- Number porting, API-driven. When the posture is to move the numbers, the number porting guide covers the shipped flow: bulk portability screening (up to 1000 numbers per check), a combined readiness pre-validation, in-platform LOA signing, per-stage timeline tracking across the port, and webhooks at each state change so cut-over is code-driven rather than calendar-driven.
- Provisioning on top. Greenfield lines, or lines you choose not to port, provision new numbers on the platform and route into the same voice surfaces as ported numbers.
What Orbit deliberately does not do: run the migration for you. Carrier selection, cut-over sequencing, and regulatory notices are tenant-owned — the platform supplies the trunk ingestion, the porting state machine, and the visibility; the migration plan is yours to execute.
A tenant-owned migration checklist
Run this per site and per carrier; nothing in it requires the incumbent's cooperation, so it can start before any notice arrives.
- Inventory every copper-fed service. Not just PBX trunks and desk phones — alarm circuits, lift phones, fax, payment terminals, door entry. For each: number(s), carrier, contract end date, and what it physically connects to.
- Get the written notice. Ask each carrier for the exchange-level withdrawal notice covering your lines, in writing. Published national dates are an upper bound; the written notice is your budget line.
- Decide posture per line group — BYO or port. Keep the carrier and point a SIP trunk (BYO) where numbering cannot move or the rate is worth keeping; port where you want one platform carrier and the porting guide's screening says the numbers are portable. Mixed estates are normal.
- Screen and file ports early. Run the bulk portability check on the whole porting list now; file the LOA and open the carrier review clock months ahead of the cut-over, not weeks.
- Stand up trunks with failover configured. Create the SIP trunks, authenticate them, and configure the failover chain while the copper still works — the migration is a routing change, not a day of downtime.
- Convert or retire the non-telephony lines. Alarms, lifts, fax: each gets an IP converter, a replacement service, or a decommissioning decision. These are the lines that fail silently after a cut-over.
- Rehearse the cut-over, then execute. Move one number group end to end, verify inbound routing and outbound egress over the platform's own termination, then migrate the remainder in tranches with a rollback window per tranche.
Frequently asked questions
What is the PSTN switch-off?
The retirement of the public switched telephone network: incumbents replace the copper access network with IP-only service, so every service riding a copper line — voice, PBX trunks, fax, alarms — must move to an IP bearer before the carrier's published cut-off for that line.
Is there one Europe-wide switch-off date?
No. The UK runs a nationally coordinated copper-retirement programme; each EU member state sets its own timetable through its national regulator and incumbents. Published dates have moved in the past, so the operative calendar is your carrier's written, exchange-level notice for your lines.
Do we have to change phone numbers when copper is retired?
No — copper retirement removes the access bearer, not the numbering. You either keep your carrier and deliver calls to the platform over a SIP trunk (BYO carrier), or port the numbers onto the platform's carrier through the regulated LNP process.
Does Orbit migrate us off PSTN for us?
No — deliberately. The migration is tenant-owned: you choose the carrier posture, sequence the cut-over, and handle the regulatory notices. Orbit ships the trunk ingestion, the API-driven porting flow, and the failover and auth visibility; the checklist above is the tenant-owned runbook that uses them.
Where does outbound calling terminate after the move?
On Orbit, outbound PSTN egress runs over Devotel's wholesale softswitch in every posture. A BYO trunk preserves your carrier for inbound delivery and the commercial relationship; it is not an alternate outbound egress.
The takeaway
PSTN switch-off is a bearer retirement, not a telephony product change — and that is why it catches estates off guard. The copper dies on a regulatory timetable you do not control; the numbers, the carrier relationship, and the migration sequence stay tenant-owned. Tenants that inventory the full copper-fed estate, pick BYO-or-port per line group, and file ports ahead of the written notice absorb the switch-off as a routing exercise. Tenants that wait for the incumbent's managed conversion absorb it as an outage with a procurement exercise attached. The news is external; the checklist is yours.
Published 12 September 2026.