Long Communications Advisory Blog

Real or Fake? How Easy It Is to Clone a Voice — and Fool the People Who Know You Best

Long Communications Ltd — Thu, 22 Oct 2026 00:00:00 +0000

Your mobile rings late in the evening. It's a number you don't recognise, but the voice on the other end is someone you love, and they sound frightened. Below are two short recordings of that kind of call. One is a real person speaking. The other is an artificial intelligence copy of that same person's voice. Have a listen to both, then pick the fake.

Which one is the AI clone?

Imagine each one is a call coming in on your mobile. Both clips say the same words. Listen to each, then choose. Headphones help, but try it on your phone speaker too, because that's how you'd really hear it.

Clip A Your browser doesn't support audio playback.

Clip B Your browser doesn't support audio playback.

Read the transcript expand_more

Both clips say the same words. The card number has been left out of this transcript.

Jasmine: Hi Ben, what's up?

Caller: I've got a problem. The car's broken down and I need your help. I need your card details.

Jasmine: Oh wow! Okay, give me a minute, let me just grab my card. It's... [card number read out].

Caller: Okay. Thanks. That's brilliant. I'll call you later to explain.

For demonstration only. The voices in these clips belong to actors who gave their full permission for them to be recorded and cloned. Never copy anyone's voice without their consent.

Think your family could tell? Send them this page.

The short version

AI can copy a voice from as little as 9 seconds of audio, using free tools, in about 30 minutes.
Phone lines strip out fine detail, and background noise hides the flaws, so fakes are very hard to hear.
The warning signs are in the situation, not the voice: an unknown number, "I'm using a friend's phone", urgency and emotion.
Hang up and ring back on a number you already have. Agree a safe word. Never approve payments on a call alone.

How close is it, really?

If you found that harder than you expected, you're in good company. The cloned voice keeps the things we instinctively use to recognise someone: the pitch, the accent, the rhythm, the little habits in how they say certain words. On a quiet recording with good headphones you might pick up a slight flatness or an odd breath. On a real phone call, in the middle of a stressful conversation, almost nobody does.

And this isn't a rare problem. Research by Starling Bank found that 28% of UK adults believe they had been targeted by an AI voice cloning scam in the previous year, while nearly half didn't know this type of scam existed at all.

How we made it, for free, in minutes

We didn't use any specialist equipment or paid software. The voice sample came from an ordinary WhatsApp call, and the clone was made using an open-source tool anyone can download. Total cost: nothing. Time taken: about 30 minutes.

The clone you heard was built from just 9 seconds of audio. Nine seconds, with no fine-tuning. Imagine how good it would sound with a few minutes of someone's voice, or a few hours of practice and polish. That's the version a determined criminal would use.

That's the uncomfortable part. Today's tools need only a few seconds of someone's voice to get started: the sort of audio that's sitting in a voicemail greeting, a social media video, a recorded webinar, or a quick phone call with a stranger who asked "Can you hear me OK?"

How the technology works (the short version)

There are two main ways AI copies a voice:

Text to speech. You type words, and the AI reads them out in the copied voice. Useful for pre-recorded voicemails and voice notes.
Speech to speech (sometimes called voice conversion). This is the one that should worry you. The scammer simply talks into a microphone, and the software swaps their voice for the cloned one as they speak. They keep their own natural timing, emotion, pauses and reactions; only the "sound" of the voice is replaced.

In simple terms, the software splits speech into two parts: what is being said (the words and delivery) and who is saying it (the unique character of the voice). It keeps the first, swaps the second, and rebuilds the audio.

Speech to speech, step by step

The scammer's words and delivery stay. Only the voice is swapped.

Bars are to scale. The swap is close to the delay you already get on every call, so you never notice it.

The reason it can work this fast is how modern models store a voice. Older approaches often had to be trained on hours of recordings of one person, and the result was slow and heavy. Newer models learn to separate the two parts of speech from the start. The "who" is squeezed into a compact voice profile, a short list of numbers that works like a fingerprint of the voice (the technical name is a speaker embedding). It is made once, from a short sample, and saved. After that the model only has to deal with the "what": the words, sounds and timing of the live speech, in tiny slices. Nothing about the voice has to be learned again during the call, so there is far less work to do each time, and each new generation of models gets quicker.

Why it's getting faster

The voice is stored separately from the words, so the heavy work is done once.

The critical point is speed. Research systems can now do this conversion in roughly 20 to 100 milliseconds, and common free tools typically run in around a fifth of a second or less. For comparison, a normal phone call already has a delay of around 150 milliseconds that we never notice. That means a criminal can hold a live, two-way conversation, answering your questions in real time, in a voice you trust.

Why the phone makes it even harder to spot

Here's the part most people don't realise: the phone network is already doing the scammer a favour.

A traditional phone call carries audio sampled 8,000 times per second. That limits the sound to frequencies up to about 3,400 Hz, roughly a third of what you'd hear standing next to the person. The crisp "s" sounds, the breathiness and the fine detail that help you spot a fake are simply cut off before they reach your ear. Everyone sounds a bit muffled on the phone, so a slightly muffled fake sounds completely normal.

How much of a voice survives the phone

The range of sound each type of call carries, from low to high pitch.

Figures are approximate and vary by network, phone and app.

Internet calling apps such as WhatsApp can carry better audio, but they automatically drop the quality when the signal is weak, which is exactly what you'd expect from someone "stuck on the hard shoulder".

Then add background noise. In our example we layered in road noise, using freely downloadable sound effects of passing traffic. It does two jobs at once:

It hides the small digital imperfections in the cloned voice.
It makes the story feel real. Your brain hears traffic and fills in the rest.

Muffled line + background noise + a familiar voice = a very convincing call.

The three tricks criminals rely on

The technology is only half the scam. The other half is psychology. Voice cloning fraud almost always leans on three things:

What makes the scam work

A convincing voice is only one ingredient. It takes all three of these together.

timer
1. Urgency: "It has to happen now."
The caller creates a deadline: the breakdown truck won't come until they're paid, the phone battery is about to die, the supplier's payment has to go today. Urgency is designed to stop you pausing, thinking, or checking with anyone else.
fact_check
2. Believability: "That could actually happen."
The story is ordinary and realistic. A family member broken down on the motorway with no bank card. A director travelling who needs an invoice paid. Nothing outlandish, just plausible enough that questioning it feels unkind or awkward.
sentiment_stressed
3. Emotion: "I'm scared, I need you."
Fear, panic, worry or guilt. Hearing someone you love sounding distressed switches off the careful, logical part of your thinking. In a business setting the emotion is often pressure from authority instead: a "senior manager" who is irritated and in a hurry. Either way, the aim is the same: make you react with your heart rather than your head.

Put all three together and even sensible, cautious people can be caught out. Many go along with it because they feel something is a bit odd but don't want to risk being wrong.

Is this legal?

No, not without permission. For this demonstration, the voices belong to actors who gave their full consent to be recorded and cloned. Doing the same to someone who hasn't agreed is a different matter, and the law treats a voice as personal.

Using a cloned voice to trick someone out of money is fraud. In the UK that is a criminal offence under the Fraud Act 2006, whatever technology is used.
A voice can be biometric data. When a voice is used to identify a person, as in a voice-recognition security check, data protection law treats it as biometric data, a special category that needs the person's explicit consent. Recording and copying someone's voice without that consent can break UK GDPR, and the Information Commissioner's Office can act on it.
Other rules can apply too. Impersonating a real person to sell or endorse something can fall foul of passing-off, defamation and performers' rights, and in some countries new laws specifically target deepfakes.

The rules are still catching up with the technology, and criminals using these tools are not worried about breaking them. That's why your own checks matter more than the law does in the moment a call comes in. This is general information, not legal advice.

How they make the story believable

The voice is only the start. Before they ring, criminals often do their homework, and for most people it takes very little effort. This is called social engineering: using ordinary, publicly available information to make a made-up story feel real.

Look at what's easy to find about almost anyone:

Where you are. A holiday photo, a "checking in" post or an out-of-office reply tells a scammer you're away, which explains an odd number, a bad line and why you can't easily check anything.
Who you know. Public friends lists, tagged photos and family members' profiles give them real names to drop into the call. "It's Dan, I've lost my phone, I'm with Sophie" sounds convincing when Sophie really is his girlfriend.
Where you work. LinkedIn and company websites show who the managing director is, who handles payments and who looks after IT, which is everything needed to aim a call at the right person.
Details leaked elsewhere. Information from past data breaches, and from earlier scam calls and texts, can supply phone numbers, addresses and birthdays.

Put a cloned voice together with a few accurate details and the caller no longer sounds like a stranger with a story. They sound like your daughter, who mentioned your dog by name and said she's stuck at the airport. The more specific the story, the more believable it feels, and the less you stop to question it.

What to look out for on the call

Almost every voice cloning scam starts the same way: a phone call, usually to a mobile, from a number you don't know. The voice may be perfect, but the situation around it rarely is. Watch for:

phone_disabled
A number you don't recognise, or none at all
Unknown, withheld or international numbers should make you cautious, especially when the caller claims to be someone close. Caller ID can be faked too, so a familiar number isn't proof either. Treat it as a hint, never a guarantee.
smartphone
"I'm using a friend's phone" or "this is my new number"
This is the classic cover story, because it explains why the number is unknown and why you can't ring them back on their own mobile. So do exactly that: hang up and ring their usual number. If they're really stuck, they'll understand.
battery_alert
"Mine's broken, lost, stolen or out of battery"
Another reason you can't call back or check. Any story that stops you verifying it should raise your suspicion, not lower it.
videocam_off
No video, no texts, no questions
A caller who can't switch to video, won't let you ring back, or dodges a simple personal question is a warning sign. So is one who asks you to keep it secret from the rest of the family or the office.
credit_card_off
Unusual ways of paying
A transfer to a new account, gift cards or crypto, "to a friend who'll sort it out". Real emergencies rarely need any of these.

What technology can do about it

You shouldn't have to catch these calls by ear alone, and some of the protection is already working for you.

Your mobile network filters known scam calls. The major UK networks block or flag calls from numbers they know are used for fraud, and Ofcom's rules require networks to stop many calls from abroad that fake a UK number. It helps, but a brand new number isn't on any list yet, and it can't tell whether the voice is real.
Your phone has its own filters. iPhones can silence unknown callers, which sends them to voicemail. Android's Phone app has spam warnings and call screening. WhatsApp can silence unknown callers too, and that matters because calls made over apps like WhatsApp don't pass through your network's scam filters at all.
Report what slips through. Forward scam texts, and report scam calls, to 7726 (it spells SPAM on the keypad). Networks use the reports to block the number for everyone else.
Detection software exists, but it's for organisations. There are services, such as Pindrop and Reality Defender, that analyse a call and flag signs of a synthetic voice, and banks and contact centres are starting to use them. Their accuracy varies, they're in a constant race against better cloning tools, and nothing like them is built into an ordinary phone call yet. Treat them as one layer of protection, not a replacement for checking.

The honest summary: technology will catch many scam calls before they ring, but a clone made from a number nobody has flagged can still get through. That's why the habits below matter.

It's not just families: businesses are targets too

The same approach works on staff: a call that sounds exactly like the managing director asking the finance team to make an urgent payment, or a "supplier" phoning to change bank details. Contact centres and help desks are also at risk, where a cloned voice could be used to pass security checks or talk an agent into resetting an account. If your phones are moving to internet-based calling after the BT switch-off, a session border controller also helps protect your phone system from fraudulent calls, although it can't tell whether a voice is real.

How to protect yourself and your business

At home

key
Agree a family safe word or phrase
Something only you know, never shared online or by text. If a "family member" calls asking for money and can't give it, hang up.
phone_callback
Hang up and call back
Use the number you already have saved, not one they give you.
help
Ask a question only the real person would know
And not one whose answer is on social media.
pause_circle
Slow down
Any request that insists you mustn't wait or check is a warning sign in itself.
public
Think about what's public
Videos and voice notes posted online are raw material for cloning. Holiday plans, tagged friends and family names give a scammer the details to make a story believable, so tighten your privacy settings and post trips once you're back.

At work

payments
Never approve a payment or bank-detail change on a phone call alone
Always confirm through a second, separate channel.
record_voice_over
Don't rely on recognising someone's voice as proof of who they are
That goes for staff on the phone and for voice-recognition security checks.
school
Train staff to spot urgency and pressure tactics
Make it clear they will never get in trouble for stopping to check.
support_agent
Review your contact centre's identity checks
Make sure they don't depend on how someone sounds.

The voice is no longer proof

The voice on the other end of the line is no longer proof of who you're talking to. The technology is free, fast and convincing, and the phone network hides its flaws for it.

Long Communications helps organisations review their telephony, contact centre and security processes so that a convincing voice alone is never enough to move money or change account details. Get in touch to talk it through.

If you think you've been targeted, report it to Action Fraud (0300 123 2040 / actionfraud.police.uk), or forward suspicious texts to 7726. If money has been sent, contact your bank straight away by calling 159.

Common questions

Can AI clone someone's voice from a few seconds of audio? expand_more

Yes. The clone in this demonstration was built from about 9 seconds of audio taken from an ordinary phone call, using a free open-source tool. With more audio the result is better still.

How can I tell if a phone call is an AI voice clone? expand_more

You usually can't by listening alone. Watch for the situation instead: an unknown number, a caller saying they are using a friend's phone or have a new number, urgency, emotional pressure, and a request for money or card details. Hang up and ring the person back on a number you already have saved.

Is voice cloning illegal in the UK? expand_more

Using a cloned voice to trick someone out of money is fraud under the Fraud Act 2006. A voice can also be biometric data, which needs explicit consent under UK GDPR, so copying someone's voice without permission can break data protection law. This is general information, not legal advice.

What should I do if someone I know calls asking for money urgently? expand_more

Hang up and call them back on the number you already have saved. Agree a family safe word in advance, ask a question only the real person could answer, and never approve a payment or bank-detail change on a phone call alone.

How do I report a voice cloning scam? expand_more

Report it to Action Fraud on 0300 123 2040 or at actionfraud.police.uk. Forward suspicious texts to 7726. If money has been sent, call your bank straight away on 159.

Sources

Starling Bank "Safe Phrases" campaign research (Mortar Research, survey of over 3,000 UK adults, September 2024)
"Low-latency Real-time Voice Conversion on CPU" (arXiv 2311.00873), for conversion speed figures

The BT Switch-Off for Business

Long Communications Ltd — Tue, 29 Sep 2026 00:00:00 +0000

Most businesses have heard of the BT switch-off. Fewer know what's actually being switched off, how many lines are still on it, or why it matters if you're not a BT customer. Here's what I tell clients.

The short answer

The UK's old copper phone network is retired on 31 January 2027. Every phone line, ISDN line, and anything else that relies on it — alarms, lift lines, card machines — needs to move to a digital service running over an internet connection. It affects every provider, not just BT.

What's being switched off, and why

For over a century, UK calls have travelled over copper wires and telephone exchanges, known as the PSTN. ISDN, the digital line behind most larger phone systems, runs over the same network. Both go. After the deadline, calls travel as data over broadband or fibre. You keep your numbers, and you can keep desk phones.

The reasons are practical. The exchange equipment is decades old, parts are scarce, faults are rising, and running a copper network alongside the new fibre one costs money that ends up in everyone's bills. It was first announced in 2017 for the end of 2025, then pushed back to January 2027 after forced migrations were paused in December 2023 following serious incidents involving telecare alarms for vulnerable people.

How many lines are still on it?

Openreach's latest estimate is around 1.2 million lines nationally, down from 1.5 million at the end of July. In September it published a breakdown for the ten largest city areas, which between them still had over 600,000 lines left:

City area	Lines left	Share not yet moved
London	235,934	12.9%
Leeds	62,411	8.6%
Manchester	55,961	7.4%
Sheffield	51,870	7.6%
Liverpool	42,351	6.4%

The North is ahead on percentages, but Leeds and Sheffield still have more lines left than Birmingham or Glasgow. London is behind on both counts. And the old lines are getting more expensive to keep: Openreach's wholesale price for them rose 20% in April and 40% in July, with a further 40% on 1 October, taking them to double their 2025 level.

Who's who

Calling it the "BT switch-off" makes it sound like a BT problem. It isn't.

Name	What they actually are
BT Group	The parent company. Owns Openreach, BT Business and EE, and runs the network being retired.
Openreach	Owns the cables, poles and exchanges. Sells to providers, not to you.
BT Business	One provider among many. Being with them doesn't change your deadline.
Sky, TalkTalk, Vodafone, most business providers	Rent Openreach's network. Affected in exactly the same way.
Virgin Media O2	Runs its own separate cable network, and is moving its own customers to digital lines too.

So talk to whoever sends you the bill, not Openreach. You don't have to move to BT. And if you have several sites, you may have several providers with several different plans. Check each one.

Will it affect our broadband?

ADSL, the oldest copper broadband, is being withdrawn. Most "fibre" broadband (fibre to the street cabinet, copper to the building) moves to a version that doesn't need a phone line, usually at the same speed. Full fibre, leased lines and Virgin Media cable carry on.

The bigger change is that your phones will now depend on your broadband. A single fault or a power cut can take out both. Ask whether you have a backup connection, what happens to calls in a power cut, and whether your main numbers can divert to mobiles automatically if the office goes offline.

What happens to international calls?

This is the question almost nobody asks, and it's where I see businesses caught out after the move.

Calling abroad still works, but check the price. International calls are often outside the bundle on new digital plans. Read the rate card before you sign, not when the first bill arrives.
Internet phone systems attract fraud. A hacked phone system can rack up thousands in international calls over a single weekend. Ask your provider to bar destinations you never call and to set a spending cap.
Calls from abroad showing your UK number can be blocked. Since January 2025, Ofcom has required UK providers to block calls from abroad that display a UK landline number, apart from a few legitimate cases. If an overseas office, an offshore call centre, or a cloud system routed through another country makes calls showing your UK number, check with your provider that it's set up properly, or those calls may never arrive.
Customers abroad calling you notice nothing, as long as your numbers are moved correctly.

Is anyone else doing this?

The UK is late, if anything. Estonia finished in 2017 and Singapore in 2020. The Netherlands and Germany have moved almost everyone, Japan moved its core network at the end of 2024, and France and Denmark are aiming for 2030. Every one of them found the same thing: moving phone calls is easy. The hard part is everything else plugged into the old lines.

If you're still on ISDN, start with my ISDN guide. If you're wondering whether you need landlines at all, read this first.

Common questions

Is the BT switch-off only for BT customers? expand_more

No. It affects every provider that uses Openreach lines, including Sky, TalkTalk, Vodafone and most business providers. Virgin Media is making the same change on its own network.

Will our phone numbers change? expand_more

No. They move with you to the new service, as long as they're moved before the old line is switched off.

Do we have to switch to BT? expand_more

No. The switch-off changes the technology, not your choice of supplier.

Does it affect mobiles or leased lines? expand_more

No. Neither relies on the old copper phone network.

Line counts from Openreach's September 2026 city figures and national updates. Price rises from Openreach's legacy line price schedule (February 2026). International calling rules from Ofcom's guidance on calls from abroad presenting UK numbers (in force since January 2025).

What Is an SBC, and Why Does Your Phone System Need One?

Long Communications Ltd — Tue, 29 Sep 2026 00:00:00 +0000

Once your phone lines move off copper and onto the internet, something has to stand at the door. That something is a session border controller. Most businesses have never heard of one, and plenty are running without one when they shouldn't be.

Where an SBC sits

Every call between your phone system and the outside world passes through it.

What an SBC is

SBC stands for session border controller. The easiest way to think of it is as border control for phone calls. Every call coming into or leaving your business passes through it, and it checks each one: is it allowed in, does it speak the right language, and is it going where it should?

It can be a physical box in your comms room, software on one of your servers, or a service run in the cloud by your provider. The job is the same either way.

Why it matters now

On the old copper network, your phone lines weren't on the internet, so nobody could reach them from the outside. That changes with the BT switch-off. Once calls travel over an internet connection, your phone system is exposed in a way it never was before, and it needs the same kind of protection your email and servers already have.

What it actually does

gpp_maybe
Stops phone fraud
Automated scanners constantly search the internet for phone systems they can break into. Once in, criminals route expensive international calls through them, usually overnight or at weekends when nobody is watching. An SBC blocks unknown callers, limits call volumes and spots unusual patterns.
translate
Translates between systems
Internet calling follows a common standard called SIP, but every manufacturer and provider speaks a slightly different dialect of it. Teams, an older on-site phone system and a phone line provider often can't talk to each other directly. The SBC sits in the middle and fixes the differences.
dialpad
Controls where calls go
It rewrites numbers into the format each side expects, decides which calls go to which provider, and can send calls to a backup route if one fails.
lock
Encrypts calls
It can scramble both the call setup and the conversation itself, so calls can't be listened in on as they cross the internet.
sync_alt
Connects old and new
During a migration, an SBC lets an old phone system and Teams run side by side, calling each other on extension numbers. Some models also have ISDN or analogue ports, which makes them the "gateway box" I mentioned in my ISDN guide for keeping an old system alive a little longer.

Do you need one?

Your setup	SBC needed?
Microsoft Teams with Direct Routing (your own phone lines)	Yes, and it must be a model Microsoft has certified
On-site phone system moving from ISDN to SIP trunks	Strongly recommended. Some providers insist on one
Old phone system and Teams running side by side	Yes. It's what joins them together
Teams Calling Plans or Operator Connect	No. The provider runs it for you
Fully hosted cloud phone system	No. It's built into the service

Examples of models

A handful of manufacturers make most of the SBCs used by UK businesses. This isn't a recommendation of any one of them; the right choice depends on the size of the site, what it connects to, and who will support it.

Manufacturer	Example models	Typically used for
AudioCodes	Mediant 500 and 800 (small sites), 2600, 4000 and 9000 (large), Mediant Virtual Edition (software)	The most common choice for Teams Direct Routing. Some models have ISDN and analogue ports
Ribbon	SBC Edge, SBC SWe (software)	Teams, larger businesses and carriers
Oracle	Enterprise SBC (formerly Acme Packet)	Large organisations and contact centres
Cisco	CUBE, which runs on Cisco routers	Businesses already built on Cisco
TE-Systems	anynode (software only)	Small to mid-sized sites, on a Windows or Linux server
Phone system makers	Avaya SBCE, Mitel Border Gateway	Protecting that maker's own phone system

Most are licensed by the number of calls they can handle at once rather than by user, so a 30-channel site buys capacity for 30 calls, not for every member of staff.

The part people forget: looking after it

An SBC isn't fit-and-forget. It needs its software keeping up to date, particularly for Teams, where Microsoft only supports specific certified versions. It also relies on security certificates that expire, and an expired certificate on an SBC can stop every call in and out of a business in one go. Whoever installs it, make sure someone owns the renewals, the updates and the monitoring afterwards.

And if it's the only route in and out for your calls, it's a single point of failure. For anything business-critical, that usually means a pair, ideally in two locations, or a managed service that builds that in.

Common questions

Do we need an SBC for Microsoft Teams? expand_more

Only if you use Direct Routing, where you bring your own phone lines. It must be a model on Microsoft's certified list. With Microsoft Calling Plans or Operator Connect, the provider runs the SBC for you.

Can our firewall do the same job? expand_more

Not really. A firewall decides whether traffic gets in. An SBC understands the phone calls themselves: it can spot fraud patterns, fix incompatible call signalling and rewrite numbers. Most businesses need both.

Does an SBC have to be a box in our building? expand_more

No. Most models also come as software that runs on your own servers or in the cloud, and many providers offer a fully managed SBC as a service.

Certified models for Teams Direct Routing are listed by Microsoft and change over time. Check the current list before buying.

"It's OK, All Our Guys Just Use Mobile Phones"

Long Communications Ltd — Tue, 29 Sep 2026 00:00:00 +0000

It's the most common thing I hear when the phone system comes up. Sometimes it's true. More often, it's true right up until someone walks into a building with no signal.

Where "just use your mobile" falls down

Typical indoor mobile signal. Illustrative; every site is different.

Open-plan office
Central London basement or tower
Steel-clad warehouse or factory floor
Next to a site that blocks signal

Signal is about the building, not the network

One Long Communications customer has premises next to government security offices, where mobile signal is deliberately blocked. Mobiles simply aren't an option there. That's an extreme case, but the everyday versions are common: tall buildings and basements in central London, modern coated glass, thick walls in older offices, and warehouses where metal cladding and racking stacked to the roof leave the far end of the floor a dead zone.

Wi-Fi calling helps only if the Wi-Fi is good everywhere, which in these buildings it usually isn't. Signal boosters exist, but only use ones that meet Ofcom's rules — many sold online aren't legal.

A phone that belongs to a person can't be shared

The goods-in phone, the reception phone, the supervisor's phone — these belong to a job, not a person. On mobiles alone there's no single number that rings a team, no queue, no recording, and customers end up with individual staff numbers. When someone leaves, the customer relationship can walk out with them.

A real example: a billion pounds of stock

I worked with a corporate warehouse holding around a billion pounds' worth of stock. It ran on phones: goods-in to picking, picking to dispatch, supervisors to the office, all day. Mobiles weren't realistic on that floor.

The warehouse had its own phone system, and its only route to the rest of the business was through an older, legacy phone system elsewhere, connected over ISDN.

When ISDN switches off, a site like that doesn't lose a few desk phones. It loses its connection to the rest of the business.

That setup isn't rare. Any site with more than about ten desk phones on its own system that hasn't been upgraded recently is likely to be on ISDN. My ISDN guide covers what to do about it.

Teams and phone apps don't fix it either

The next suggestion is usually "put everyone on Teams". That's fine for office staff, but it doesn't work for a seasonal or shift workforce. Seasonal workers often have no company email, laptop or Microsoft licence, a per-user licence for six weeks rarely makes sense, and nobody wants a laptop halfway up a racking aisle. They need a phone they pick up at the start of a shift and hand back at the end.

Mobiles cost more than they look

UK minutes are bundled, but international calls usually aren't, and roaming adds more. Across a team, those are the lines on the bill nobody checks. There's a newer wrinkle too: under Ofcom's tightened anti-scam rules, calls from abroad showing a UK mobile number can have their caller ID withheld unless the network can verify them. Staff calling UK customers from a trip abroad may find their number doesn't show, and the call goes unanswered.

What actually works

Landlines aren't dead; they've changed. For warehouses, factories and busy receptions the answer is usually a mix: cordless (DECT) phones running over the site's own network, which don't care about mobile signal; shared phones and team numbers for the roles that need them; and mobiles for managers and field staff, linked to the phone system so they keep a work number.

If you're not sure which camp you're in, walk the site with a phone and watch the signal bars. It's the cheapest survey you'll ever do.

Common questions

Can we move our 01 or 02 number onto a mobile? expand_more

Not directly onto a mobile SIM. You can keep the number on a cloud phone service and have it ring mobiles or an app, so customers still see the number they know.

What's the best phone for a warehouse with poor signal? expand_more

Usually a cordless (DECT) system with rugged handsets running over the site's own network, with enough base stations to cover the whole floor.

Does the switch-off matter if we mainly use mobiles? expand_more

It can. Any lift line, alarm, door entry or card machine still on the old network needs moving before 31 January 2027.

Caller ID point based on Ofcom's guidance on calls from abroad presenting UK numbers (2025–26).

What Is ISDN?

Long Communications Ltd — Tue, 29 Sep 2026 00:00:00 +0000

ISDN stops working on 31 January 2027. In 25 years of working on business phone systems, I've found it's rarely the phones that cause the trouble. It's everything wired into them that nobody wrote down.

Where we are

Openreach has confirmed there will be no further extensions.

What ISDN actually is

ISDN is the digital line that connects an on-site phone system — the box in the comms cupboard — to the outside world. ISDN2 carries two calls at once and is common in small offices. ISDN30 comes in blocks of up to 30 channels, one call per channel, and sits behind larger offices, hospitals, councils and contact centres. Both usually come with a block of direct-dial numbers.

A useful rule of thumb: if a site has more than a handful of desk phones on its own phone system and nobody has touched it in ten years, assume it's on ISDN until someone proves otherwise.

Where things stand

Openreach's latest estimate is around 1.2 million lines still on the old network, down from 1.5 million at the end of July. About 350,000 of the July figure were business premises — and the business number Openreach quoted in September hadn't moved since.

Nobody publishes a separate count of ISDN circuits. But the fact the business figure has stalled tells you something: the sites left aren't the ones who forgot. They're the ones where it's genuinely complicated.

What happens on the day

The line goes dead. There's no dial tone, and anyone ringing your numbers hears an unobtainable tone, so to a customer you look closed. Anything that dials out over the line — an alarm panel, a lift phone — fails silently. You find out when it's needed.

Your numbers need moving to a new provider while the old line is still live. Once a line is ceased, getting its numbers back is difficult and not guaranteed. Openreach has announced a last-resort safety net for some lines that miss the deadline, but it's temporary, costs more, and isn't something any business should plan around.

What else goes with it

emergency
999 calls
If the desk phones are the only phones on site, nobody can call 999 from them. After you move, the address sent to emergency services has to be set correctly for every site.
elevator
Lift emergency phones
Often plugged into a spare port on the phone system, so they get missed. They must work in a power cut, and a lift without one usually has to come out of service.
notifications_active
Fire and intruder alarms
The alarm may still sound on site, but the monitoring centre never hears about it. Worth checking with your insurer.
point_of_sale
Card machines, door entry, fax and franking
Older kit that dials out, still more common than people expect.
headset_mic
Contact centres
Queues, menus, wallboards and call recording all sit behind the ISDN channels. Some older recorders tap the line directly and stop without anyone noticing. In a regulated business, that's a compliance problem, not an IT one.

What it's costing you now

£9k–£18k

Typical yearly line rental for one 30-channel ISDN30 circuit, before call charges, at £25–£50 per channel per month.

The replacement lines usually cost a fraction of that. Meanwhile, the analogue lines that often sit alongside ISDN for lifts and alarms are getting dearer fast: Openreach raised their wholesale price by 20% in April and 40% in July, and a further 40% rise on 1 October takes them to double their 2025 level. Add the cost of keeping an out-of-support phone system alive, plus the premium for anything done in a December rush, and waiting is the expensive option.

Your three options

Route	Fits when	Main risk
Keep the phone system, swap ISDN for SIP trunks	The system is still supported and can take SIP (phone lines delivered over a data connection)	Relying on a single internet connection
Replace the phone system	It's out of support, or staff work from home some of the time	Call routing and queues don't transfer automatically
Drop the phone system, use mobiles	A small, mobile team with good signal everywhere	Losing shared lines, queues and in-building coverage

My view: if the phone system is still supported, move the lines to SIP first and replace the system later. It turns one risky project with a hard deadline into two calm ones. Mobiles-only works for some businesses, but it's not as simple as it sounds — I've written about why.

Two things to get right whichever route you take. First, 30 calls need only around 3 Mbps, so capacity is rarely the issue — having a second connection by a different route is. Second, if the old system can't take SIP at all, a gateway box can buy time, but agree an exit date before you install it.

A quick word on VoIP phones

VoIP phones plug into the network socket rather than the phone socket. If you keep your phone system, your handsets stay. If you replace it, the digital handsets from older Avaya, Mitel or Panasonic systems usually won't come with you. Most VoIP phones are powered through the network cable, so they go off in a power cut unless your network kit has battery backup. And order early: popular models will go on backorder as January gets closer.

Common questions

Can we keep our phone numbers? expand_more

Yes, including your full block of direct-dial numbers, as long as they're moved to the new provider before the ISDN line is ceased. Never cancel the old line until the transfer has completed and been tested.

Do we have to replace our phone system? expand_more

Not if it's still supported and can take SIP trunks. If it's out of support, the switch-off is usually the right moment to replace it rather than pay to keep it limping on.

How do we know if we still have ISDN? expand_more

Check the phone bill for ISDN2, ISDN30, channels or a range of direct-dial numbers, and look near the phone system for a BT or Openreach box labelled ISDN.

Figures from Openreach's published updates (July and September 2026) and its legacy line price schedule (February 2026). ISDN rental range is typical of UK provider pricing.

The Hidden Cost of Microsoft Teams

Long Communications Ltd — Tue, 15 Sep 2026 00:00:00 +0000

Microsoft Teams often gets bought as "the free bit that comes with Microsoft 365." Calling never was — and five years of quiet UK price rises have made that gap an expensive one.

UK list price · ex VAT

Teams Phone: cost per user, per month

Since 2021 +79%

Teams Phone Standard + UK domestic calling plan, standard published Microsoft list prices, 2021–2026, rounded to the nearest 10p. Illustrative trend based on published price changes.

Ten pounds became eighteen

In 2021, giving one person a Teams-based UK phone line — the Phone Standard licence plus a domestic calling plan — cost around £10 a user, per month, on Microsoft's UK list price. By 2026, that same combination lists at roughly £17.90. That's a 79% rise, and almost none of it arrived as one dramatic announcement. It came in instalments: a currency-linked price adjustment in 2023, a licensing restructure in 2023/24, and a further list price increase moving into 2025/26 — each one small enough to wave through at renewal, each one compounding on the last.

The E3 licence that quietly got smaller

A lot of UK businesses standardised on Microsoft 365 E3 partly because it seemed to include "everything," Teams client included. That changed. Following EU regulatory pressure, Microsoft unbundled Teams from the E1/E3/E5 suites, so the client itself now carries its own line item — before calling is even switched on. Meanwhile, plenty of what E3 and E5 customers already pay for goes largely unused: most staff join a handful of Teams calls a week and never touch the rest of what the licence includes.

None of this is a knock on Microsoft

To be clear, this isn't personal against Microsoft. Teams is a genuinely capable product, and Microsoft has poured serious, sustained investment into it — calling features, AI-assisted meetings, device support, and tighter integration across the wider Microsoft 365 stack. The issue isn't quality, it's usage. Before the next renewal, it's worth asking a blunt question: how much of what you're licensed for do the people using Teams every day actually touch? If the honest answer is "not much," you may be paying premium rates for a version of Teams your business isn't really using.

Paying full price for a phone some people barely use — and can't use at all

Per-user licensing assumes every seat needs the same thing. In practice, some staff make almost no external calls and would manage fine on far less than a full calling licence. Others — anyone based in a basement, a warehouse, or a signal-shadowed corner of a site — can't rely on Teams at all, because there's no dependable Wi-Fi or mobile signal to run it on. Those people still need a physical desk phone or DECT handset, wired to a line that has nothing to do with Microsoft. So the real bill isn't just the rising Teams number on its own — it's Teams for the desks that can use it, plus hardware and lines for the ones that can't, priced separately and rarely reviewed together.

The licence is only half the bill

Every figure above is just the Microsoft licence — the right to make and receive calls in Teams. Actually connecting those calls to a real landline or mobile number, out on the UK phone network, is a separate cost again, bought one of three ways:

Calling Plans — Microsoft's own PSTN service, bundled minutes bought straight from Microsoft on top of the Phone Standard licence. Simplest to set up, but it's Microsoft's own metered rates, and the domestic add-on alone commonly runs another £4.80–£6.00 a user, per month, in the UK — on top of everything already covered above.
Operator Connect — a third-party carrier plugs directly into Microsoft's cloud, so there's no on-site hardware to run. The carrier bills you separately from Microsoft, on its own contract and its own rates — often cheaper per minute at any real volume, but it's a second invoice, from a second supplier, that rarely gets checked against the first.
Direct Routing — you connect your own carrier and a session border controller (physical or "as a service") into Teams. Frequently the cheapest per-minute option, especially if a carrier contract is already in place, but it adds the cost of that hardware or platform, plus someone to keep it patched and secure.

None of these is right or wrong — each suits a different size and shape of business. But whichever one gets chosen sits on top of the per-user licence, on a different bill, often bought at a different time by a different person. Add licensing and connectivity together, rather than reviewing them separately, and the true monthly cost of "just giving someone a phone" is usually a good deal higher than the licence price alone suggests.

Why it creeps up on you

None of these changes needed sign-off from most finance teams — they landed as routine renewal terms, not projects. That's exactly why the number is worth checking against what your business actually uses, rather than what got bought three renewals ago.