How much internet speed do I need for international VoIP calls?

A single voice call needs roughly 100 kbps in each direction, which is very little. Quality problems on international calls are almost never about bandwidth and almost always about latency and jitter — the consistency of the connection rather than its speed. A stable connection at modest speed will outperform a fast but unstable one.

4 Months Left Before Openreach Shuts Down UK PSTN

What is actually happening?

The PSTN is the analogue network of copper wires and telephone exchanges the UK has used since the 1800s. BT Group is retiring it because it's old, expensive to maintain, and can't carry the bandwidth modern services need. Everything moves to digital, IP-based services instead — calls travel over the internet rather than dedicated copper lines.

Alongside the network itself, Openreach is withdrawing every product that runs on it — the Wholesale Line Rental (WLR) products your phone provider resells to you. That's why your provider may have already written to you about migration, and why legacy line rental prices have been rising: Openreach has confirmed tiered price increases on legacy WLR products in the run-up to the deadline.

HOW WE GOT HERE
2017	BT announces its intention to retire the PSTN, with December 2025 as the original switch-off date.
Sept 2023	"Stop sell" takes full effect — providers can no longer sell new PSTN-based products anywhere in the UK.
May 2024	The deadline is pushed back 13 months to 31 January 2027, after serious incidents involving vulnerable telecare users during migrations prompted more caution across the industry.
July 2026	Openreach launches its "Big Switch Off" campaign at the six-month mark, estimating 1.5 million lines still on copper — including ~350,000 business premises — and confirming no further extension.
31 Jan 2027	The PSTN and all Wholesale Line Rental (WLR) products are withdrawn. Anything still on copper stops working.

What stops working on 31 January 2027

The obvious casualty is the traditional landline. But the bigger risk for businesses is the equipment that quietly depends on a copper line — services that often sit outside normal IT planning, which is why so many firms don't realise they're exposed:

Analogue landlines

Every traditional phone line, home or business, goes silent.

ISDN phone systems

ISDN2 and ISDN30 lines behind office PBX systems are withdrawn.

ADSL & FTTC broadband

Copper-based broadband is retired too — not just voice.

Card payment terminals

Older terminals that dial out over a phone line stop processing.

Security & fire alarms

Alarm signalling that dials a monitoring centre over copper fails.

Lift emergency lines

Auto-dialler emergency phones in lifts need a digital replacement.

Fax machines & franking

Anything with a phone socket and a dial tone is affected.

Telecare & personal alarms

Analogue pendant alarms must move to digital equivalents.

What happens if you wait?

Openreach's warning to late movers is blunt: those who leave it to the final weeks risk avoidable disruption and cost. In practice, waiting means three things:

Rising costs on a dying network

Openreach has confirmed tiered price increases on legacy WLR products in the final stretch. Staying on copper gets more expensive every quarter until it stops working entirely.

The January bottleneck

Hundreds of thousands of lines still need migrating. Engineers, number ports and provider onboarding all get slower as everyone rushes at once — the businesses moving in December and January will queue.

Silent failures you did not plan for

Openreach's own concern is the lines businesses forgot about — the alarm, the lift phone, the card machine. When copper goes quiet, these fail without warning unless they were audited and moved.

Your 4-month migration checklist

Four months is still enough time to migrate calmly — if you start now. Here's the order to do it in:

Audit every line — this week

List every phone number and every device with a phone socket: main lines, DDIs, fax, alarms, lifts, door entry, payment terminals. Ask your current provider which of your services run on PSTN/WLR — they can see it.

Sort lines into "voice" and "not voice"

Phone lines move to a cloud phone system. Alarms, lifts and terminals need digital replacements from their own vendors — start those conversations now, as hardware lead times grow near the deadline.

Choose your cloud phone provider

Compare on the features you'll actually use: call routing, IVR, mobile apps, call recording — and what happens to calls nobody can answer.

Port your numbers early

Number porting is the step with a queue. Submitting your port in October means a calm switchover; submitting in January means hoping. Your number stays live during the port.

Run both in parallel, then cancel copper

Test the new system alongside the old line for a week or two — call flows, voicemail, opening hours. Then cancel the copper service and stop paying rising WLR prices for a network about to vanish.

The replacement: cloud phones

Moving from the PSTN to a cloud phone system changes where your calls are handled rather than taking your business number away. Your existing number can be ported to the new provider, while calls can be answered through desktop, mobile or compatible desk phones and managed through software instead of copper-line hardware.

Legacy PSTN	Cloud Phone System
One line, one desk, one place to answer	Answer on mobile, desktop or desk phone — anywhere
Engineer visits and new wiring for changes	Changes made in a dashboard in minutes
Missed call = lost caller	IVR, ring strategies and AI answering catch every call
Rising WLR line rental on a closing network	From $12/user/month billed annually, all features included
No record of who called or why	Call history, recording and AI call summaries

Move Your Business Calls Off Copper

Port your existing numbers to Calilio, build your call flow and IVR, and answer calls from desktop, mobile or AI before the PSTN deadline.

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Frequently Asked Questions

When exactly is the UK PSTN switch-off?

31 January 2027. BT Group retires the PSTN and Openreach withdraws all Wholesale Line Rental products that run on it. The date was originally December 2025, was extended once in May 2024, and Openreach has confirmed there will be no further extension.

Will my phone number change when I leave the landline?

No. You port your existing number to your new provider — it moves with you, and it stays live during the transfer. Porting a UK number to a cloud system like Calilio typically takes days.

Does the switch-off affect broadband too?

Yes, if your broadband is copper-based. ADSL and FTTC (fibre-to-the-cabinet) connections run over the same network being retired, so they're moving to full-fibre or other digital alternatives as part of the same programme.

What about our alarm system, lift phone and card machine?

These are the highest-risk items because they fail silently. Each needs a digital replacement from its own vendor — your alarm monitoring company, lift maintainer and payment provider all have PSTN migration paths. Start with an audit of every device that plugs into a phone socket.

Is a VoIP system harder to use than a landline?

It's simpler day to day. Calls arrive in an app on the phones and computers you already own, and features that needed engineer visits on copper — call menus, opening hours, forwarding — are settings you change yourself in minutes.

What does a replacement system cost?

Cloud phone systems typically cost $10-35 per user per month — usually less than business line rental plus call charges on copper. Calilio starts at $15/user/month ($12 billed annually) including IVR, ring strategies, call recording and an AI Voice Agent with free monthly minutes.