For years, “do nothing” was a defensible enterprise telephony strategy.
If the PBX was stable and nobody was shouting, extending the life of on‑prem voice could look like prudent asset management: sweat the hardware, renew support, and revisit the problem “next year.”
In 2026, that logic is collapsing. As the UK’s PSTN switch‑off in January 2027 approaches, the “do nothing” option is increasingly priced like a premium service: harder to staff, more expensive to maintain, and riskier to run.
Doug Jones, AVP of Product Management & Development – Collaboration at AT&T, describes one common form of the problem as simple duplication.
“First and foremost, it’s having multiple telephone numbers with multiple calling plans,” he said in a recent UC Today interview.
“Enterprises, in far too many cases, have a desk phone in their office and a phone number on their mobile at a minimum. You don’t really need both of them, obviously, since it’s duplicative.”
That duplication pattern is now showing up in architecture: UCaaS or Teams calling on top, a legacy PBX estate underneath, and a shrinking PSTN footprint that costs more each quarter.
The “do nothing” tax is becoming explicit
Openreach is now pricing legacy copper like a sunset product. WLR wholesale rental rises in 2026: +20% (1 Apr), +40% (1 Jul), +40% (1 Oct): effectively doubling versus today’s £10.65 baseline.
James Lilley, Openreach’s Managed Customer Migrations Director, has been explicit about the intent.
“We need to accelerate the pace of migration to ensure no customer is left behind,” he said. “These price adjustments are designed to drive action, while our special offers help make the transition smoother for everyone.”
“The PSTN analogue network is obsolete, becoming harder to maintain and significantly more expensive to run,” he claimed. “We are passing those costs on to providers who continue to sell legacy products.
"If your business is still on this copper service, you will start to pay a premium for a service that will be switched off in 12 months.”
Bottom line: “do nothing” is no longer cost‑neutral.
Why “we moved to the cloud” doesn’t always reduce spend
One reason the cost spike catches finance teams off guard is that many enterprises believe they already “solved telephony” by moving users to a UCaaS platform.
But the PSTN switch‑off is exposing a messier truth: a lot of cloud voice programmes were partial migrations. Users moved, yet numbers, call paths, special services, and contracts often remained: which means the legacy cost base never truly switched off.
That has created a visibility gap which is exactly where dual‑run spend hides: duplicated contracts, duplicated operational processes, and “temporary” workarounds that become permanent.
It also reinforces why migration is rarely a one‑off. As Algo CEO Ryan Zoehner put it in a UC Today interview: “You’re probably committing to a migration here that’s a journey, not a one‑time activity.”
The lesson for buyers is uncomfortable but simple: cloud calling licences don’t automatically retire the PBX costs, you have to run a deliberate exit programme to unwind numbers, lines, routing, resiliency, and the long tail of edge cases.
The scarcity premium: legacy skills and parts don’t get cheaper
Meanwhile, the “keep it running” side of the equation is also changing.
Legacy PBX estates don’t only cost money in contracts. They cost money when they fail, and the support ecosystem is shrinking.
According to Ed Savory, Business Development Director at Gamma:
“The skillset of engineers who maintain these older systems is becoming more scarce, and sourcing replacement parts is expensive, if not impossible. If a PBX fails, businesses may find themselves without a viable solution, causing major disruptions.”
Vendor timelines compress “optional” decisions
Vendor roadmaps create another pressure: the window to extend legacy systems safely is narrowing.
Continuant’s David Shelby, whose organisation has long supported legacy voice estates, highlights a timeline many enterprises may not have internalised.
“The PBX is dead,” he wrote in May 2025. “Avaya’s last PBX, the Avaya Aura, will be in End of Manufacturer Support by the end of 2026.”
