How to Reduce Business Phone Costs with VoIP

For most UK businesses, the phone system is one of those expenses that quietly drains the budget month after month without anyone questioning it. Line rental charges from BT or Virgin Media, per-minute call rates, expensive maintenance contracts for ageing PBX hardware, and the occasional eye-watering international call bill — it all adds up to a significant and often unnecessary cost burden.

The good news? Voice over Internet Protocol (VoIP) has matured into a reliable, feature-rich alternative that can slash business phone costs by 40–70% for most UK SMEs. And unlike the early days of internet calling — plagued by choppy audio and dropped connections — modern VoIP delivers call quality that is indistinguishable from traditional landlines, with a host of powerful features included at no extra cost.

This guide breaks down exactly where your money is going with traditional telephony, how VoIP pricing works, and provides a practical framework for calculating the real savings your business could achieve by making the switch.

The True Cost of Traditional Phone Systems in the UK

Before we look at how VoIP saves money, it is essential to understand exactly where your current telephone budget is going. Most businesses significantly underestimate what they actually spend on telephony because the costs are fragmented across multiple invoices, contracts, and suppliers.

Line Rental and Call Charges

Every traditional phone line in the UK requires a rental agreement with a provider such as BT, Virgin Media Business, or TalkTalk Business. As of 2024, BT Business line rental sits at approximately £17–£22 per month per line, depending on the contract. For a business with 20 employees, each needing their own direct line, that alone amounts to £4,200–£5,280 per year — before a single call is made.

Call charges add another layer of cost. While local and national rates have fallen over the years, they still typically range from 2p–10p per minute depending on the destination and time of day. Mobile calls from landlines remain particularly expensive at 8p–15p per minute with many providers. For sales-heavy businesses making hundreds of outbound calls per day, this quickly becomes a four- or five-figure annual expense.

International calls are where traditional telephony costs truly spiral. Calling a European landline from a BT business line costs around 6p–20p per minute, while calls to the US average 10p–25p per minute. Destinations in Asia, Africa, and the Middle East can exceed £1 per minute. For UK businesses with overseas clients, suppliers, or remote teams, these charges can add thousands of pounds to the annual phone bill.

Hardware and PBX Systems

Traditional business phone systems rely on a Private Branch Exchange (PBX) — a physical piece of hardware installed on your premises that routes calls between internal extensions and external lines. A new on-premise PBX system for a 20-user office typically costs between £3,000 and £10,000 upfront, depending on the manufacturer and feature set. Premium brands like Avaya, Mitel, and Cisco can push costs even higher.

On top of the PBX itself, each employee needs a desk phone. Business-grade handsets from manufacturers like Yealink, Polycom, or Cisco range from £60 for basic models to £250+ for executive phones with colour screens and Bluetooth. For 20 handsets, budget £1,200–£5,000.

The total initial outlay for a traditional system — PBX hardware, handsets, cabling, and installation — routinely falls between £5,000 and £20,000 for a small-to-medium business. That is a significant capital expenditure that must be depreciated over 5–7 years, during which time the technology will inevitably age and require replacement.

Maintenance and Support Contracts

On-premise PBX systems require ongoing maintenance. Most businesses take out an annual support contract with their telephony provider or a third-party maintenance company, typically costing between £500 and £2,500 per year depending on the size and complexity of the system. These contracts cover software updates, fault resolution, and occasional hardware replacement — but they rarely cover major component failures or system upgrades, which are charged separately.

When a PBX system fails outside of business hours or experiences a critical fault, emergency call-out charges of £100–£250 per hour are common. For businesses without a maintenance contract, even a routine repair can cost £300–£600 for a single visit.

The Hidden Cost of Inflexibility

Perhaps the most significant cost of traditional phone systems is one that never appears on an invoice: inflexibility. Adding new extensions requires physical cabling and configuration by an engineer (typically £50–£150 per extension). Moving offices means decommissioning the entire system and reinstalling it at the new location — a project that can easily cost £2,000–£5,000 and cause days of disruption. Scaling down is equally painful, as you are often locked into multi-year line rental contracts with early termination fees.

For UK businesses navigating the shift to hybrid and remote working, traditional phone systems present an even greater challenge. There is simply no easy way to route calls to home workers without expensive call-forwarding arrangements or separate mobile phone contracts, each adding further cost and complexity.

Understanding VoIP: A Brief Overview

VoIP (Voice over Internet Protocol) transmits voice calls as data packets over the internet rather than through traditional copper telephone lines. Instead of a physical PBX on your premises, the call-routing intelligence sits in the cloud, managed by your VoIP provider. Calls can be made and received from desk phones, laptops, tablets, or mobile phones — anywhere with a broadband connection.

Modern business VoIP systems (often called Hosted PBX or UCaaS — Unified Communications as a Service) bundle voice calls with a suite of features that would cost thousands extra on a traditional system: auto-attendant, call queuing, voicemail-to-email, call recording, video conferencing, instant messaging, and CRM integration are all typically included as standard.

The underlying technology has improved dramatically. With a stable broadband connection of at least 100 Kbps per concurrent call (well within the capability of any modern business broadband package), VoIP call quality now matches or exceeds traditional landlines. HD Voice, available on most VoIP platforms, actually delivers superior audio clarity compared to the narrowband codecs used by the legacy telephone network.

VoIP Pricing Models Explained

One of the advantages of VoIP is pricing transparency. Unlike traditional telephony — where costs are fragmented across line rentals, call bundles, PBX leases, and maintenance contracts — VoIP providers typically offer straightforward per-user or per-line monthly pricing. Here are the three most common models used by UK VoIP providers.

Per-User Pricing

The most popular model for SMEs. You pay a fixed monthly fee per user, which includes a phone number, a set number of inclusive minutes (or unlimited calls), and access to the full feature set. Prices across UK providers typically range from £8–£25 per user per month, depending on the feature tier and inclusive minutes.

This model works well for businesses where every employee needs their own extension and phone number. It scales cleanly — adding a new starter is as simple as provisioning a new user in the admin portal, with no engineer visit or hardware installation required.

Per-Line (Channel) Pricing

Some providers charge per concurrent call channel rather than per user. A channel represents one simultaneous call, so a business that never has more than 10 calls happening at once only needs 10 channels — even if it has 50 employees. Pricing typically ranges from £5–£15 per channel per month.

This model can offer significant savings for businesses with large teams but relatively low concurrent call volumes, such as professional services firms or creative agencies where not everyone is on the phone at the same time.

Unlimited / All-Inclusive Plans

Premium plans that bundle unlimited UK landline and mobile calls, international minutes to key destinations, and the full feature suite into a single per-user fee. These typically cost £20–£35 per user per month but eliminate any risk of bill shock from overage charges. They are ideal for sales teams, call centres, and businesses with high outbound call volumes.

Typical Monthly Costs by Plan Type

Traditional Telephony vs VoIP: A Direct Comparison

To make the difference concrete, here is a head-to-head comparison of what you get with a modern VoIP system versus a traditional on-premise PBX setup.

Where the Real Savings Come From

The cost advantage of VoIP is not a single dramatic saving in one area — it is the cumulative effect of reductions across every component of your telephony spend. Here is a detailed breakdown of where those savings materialise for a typical UK SME.

1. Eliminating Line Rental

This is the single biggest and most immediate saving. VoIP calls travel over your existing broadband connection, so there is no need for dedicated telephone lines from BT or any other provider. For a business currently paying £20 per month for each of 20 lines, that is an immediate saving of £4,800 per year.

With the PSTN (Public Switched Telephone Network) and ISDN switch-off well underway in the UK — BT has confirmed the complete shutdown by January 2027 — every business will eventually need to move to an IP-based solution regardless. Making the switch proactively means you start saving now rather than being forced into a potentially rushed and more expensive migration later.

2. Slashing International and Mobile Call Costs

VoIP providers offer dramatically lower international call rates because calls are routed over the internet for the majority of their journey, only connecting to the local telephone network at the destination end. Typical VoIP rates for popular business destinations include:

Destination	Traditional BT Rate	Typical VoIP Rate	Saving
USA (landline)	10p–25p/min	1p–2p/min	Up to 92%
EU countries (landline)	6p–20p/min	1p–3p/min	Up to 85%
India (landline)	20p–60p/min	2p–5p/min	Up to 92%
Australia (landline)	12p–30p/min	1p–3p/min	Up to 90%
UK mobile	8p–15p/min	Included or 1p–2p/min	Up to 87%

For a UK business making just 500 minutes of international calls per month, the annual saving could easily exceed £1,000–£3,000 depending on the destinations. Businesses with offshore teams, international clients, or global supply chains will save considerably more.

3. Reducing Hardware Expenditure

With VoIP, the physical PBX box in your server room is replaced by cloud infrastructure managed by your provider. That eliminates the £3,000–£10,000 upfront hardware cost entirely. But the savings go further still.

Many businesses deploying VoIP opt for softphones — software applications installed on existing laptops, desktops, or mobile phones — rather than dedicated desk handsets. This approach means the hardware cost per user drops to £0, since employees use devices they already have. For businesses that prefer physical handsets, modern VoIP desk phones from manufacturers like Yealink cost as little as £40–£80 each, significantly less than the premium handsets required by many legacy PBX systems.

A headset for softphone use typically costs £25–£80 — a fraction of the £100–£250 per handset that a traditional system demands. For a 20-user deployment, choosing softphones with headsets instead of desk phones saves £1,500–£4,000 in hardware costs alone.

4. Removing Maintenance Contracts

Because the phone system infrastructure lives in the cloud, there is no on-premise hardware to maintain, patch, or repair. Your VoIP provider handles all updates, security patches, and system maintenance as part of the monthly subscription. This eliminates the £500–£2,500 annual maintenance contract, plus any ad-hoc engineer call-out fees.

System updates and new features are rolled out automatically by the provider, meaning your phone system actually improves over time without any additional cost or effort on your part. Compare this with traditional PBX systems, where firmware updates require scheduled engineer visits and feature upgrades often mean purchasing entirely new hardware modules.

5. Consolidating Multiple Systems

Many UK businesses are currently paying separately for their phone system, a conferencing service (like a dedicated bridge number), a call recording solution, and perhaps a separate mobile phone contract for staff who work remotely. VoIP consolidates all of these into a single platform with a single monthly bill.

A typical consolidation saving looks like this:

Service	Separate Cost (Monthly)	VoIP Equivalent
Phone system (lines + calls)	£600–£1,200	Included in VoIP subscription
Conference bridge service	£50–£150	Included (video & audio)
Call recording	£30–£100	Included
Mobile phone contracts (10 users)	£200–£400	VoIP app on personal mobiles
Fax line rental	£15–£20	Virtual fax included or £2/mo

The consolidation effect alone can save £3,000–£10,000 per year for a 20-person business, while simultaneously simplifying administration and reducing the number of vendor relationships you need to manage.

Hidden Costs to Watch For

While VoIP delivers genuine and substantial savings, it is important to go in with your eyes open. Not every provider is transparent about their pricing, and there are a few potential pitfalls that can erode your savings if you are not careful.

Number Porting Fees

Transferring your existing phone numbers to a new VoIP provider (known as number porting) is usually free or costs a small one-off fee of £5–£15 per number. However, some providers charge £25–£50 per number, which can add up if you have a large bank of DDI (Direct Dial-In) numbers. Always confirm porting costs upfront.

Premium and Non-Geographic Number Charges

While UK landline and mobile calls are typically included or very cheap, calls to premium rate numbers (09xx), directory enquiries (118xxx), and some non-geographic numbers (084x, 087x) may be charged at significantly higher rates. Review the provider’s rate card for these number ranges if your business regularly calls them.

Contract Lock-In Periods

Some VoIP providers offer lower monthly rates in exchange for 24- or 36-month contract commitments, with substantial early termination fees. If flexibility is important to you, look for providers offering monthly rolling contracts, even if the per-user rate is slightly higher. The freedom to switch or scale without penalty is often worth the premium.

Broadband Dependency

VoIP relies entirely on your internet connection. If your broadband goes down, so do your phones. This is not a hidden cost per se, but it is a risk you need to mitigate. Ensure you have a business-grade broadband connection with an SLA, and consider a backup 4G/5G failover solution (typically £20–£40 per month) for critical continuity. Most reputable VoIP providers can automatically redirect calls to mobile numbers during an outage, but this must be configured in advance.

Add-On Feature Charges

While most VoIP providers include a generous feature set as standard, some charge extra for features like call recording storage beyond a certain period, CRM integration, advanced analytics, or wallboard displays for call centres. Clarify which features are included in your chosen plan and which carry additional fees.

ROI Calculation Framework

To build a compelling business case for switching to VoIP, you need a structured approach to calculating your return on investment. Here is a practical framework that accounts for all the major cost categories.

Step 1: Calculate Your Current Annual Telephony Spend

Gather the last 12 months of invoices and total up every telephony-related cost:

• Line rental (all PSTN/ISDN lines)
• Call charges (local, national, mobile, international)
• PBX lease or depreciation
• Maintenance and support contracts
• Conference call services
• Call recording solutions
• Mobile phone contracts (if used for business calls)
• Any ad-hoc engineer or repair charges

Step 2: Calculate Your Projected VoIP Cost

Get quotes from two or three reputable UK VoIP providers and calculate the total annual cost including:

• Per-user or per-channel monthly fees × 12
• Any one-off setup or porting fees
• Hardware costs (handsets or headsets, if required)
• Broadband upgrade costs (if your current connection is inadequate)
• Any add-on features you need

Step 3: Calculate the Net Annual Saving

Subtract your projected VoIP cost from your current spend. Then factor in the one-off migration costs (porting, hardware, any broadband upgrades) spread across the first year. The result is your first-year saving. From year two onwards, the saving increases as those one-off costs drop away.

Typical Savings by Category

Based on our experience migrating hundreds of UK SMEs to VoIP, here is where the savings typically break down:

Real Savings: UK SME Examples

To bring the numbers to life, here are three realistic scenarios based on the types of UK businesses we work with regularly. All figures represent annual costs.

Scenario	10-Person Accountancy Firm	25-Person Recruitment Agency	50-Person Professional Services Firm
Traditional: Line rental	£2,640	£6,600	£13,200
Traditional: Call charges	£960	£4,800	£6,000
Traditional: PBX depreciation	£600	£1,200	£2,400
Traditional: Maintenance	£500	£1,200	£2,500
Traditional: Other (conferencing, recording)	£600	£1,800	£3,600
Traditional Total	£5,300	£15,600	£27,700
VoIP: Monthly subscription	£1,800 (£15/user)	£5,400 (£18/user)	£9,600 (£16/user)
VoIP: Year 1 setup costs	£200	£400	£750
VoIP Total (Year 1)	£2,000	£5,800	£10,350
Annual Saving (Year 1)	£3,300 (62%)	£9,800 (63%)	£17,350 (63%)
Annual Saving (Year 2+)	£3,500 (66%)	£10,200 (65%)	£18,100 (65%)

Making the Switch: What to Consider

Convinced by the numbers? Here are the key considerations to ensure your VoIP migration goes smoothly.

Broadband Readiness

Each concurrent VoIP call requires approximately 100 Kbps of bandwidth. For a 20-user business where a maximum of 10 calls might be active simultaneously, that is 1 Mbps — well within the capability of virtually any business broadband connection. However, consistency and low latency matter more than raw speed. Ensure your broadband provider offers a connection with jitter below 30ms and latency below 150ms. Most fibre and leased-line connections comfortably meet these thresholds.

If your current broadband is unreliable, consider upgrading to a dedicated business fibre connection or a leased line before deploying VoIP. The cost of a broadband upgrade (£30–£100 per month for fibre, £150–£400 per month for a leased line) is almost always offset by the telephony savings.

Number Porting

Your existing phone numbers — including geographic numbers, non-geographic numbers, and freephone numbers — can almost always be ported to your new VoIP provider. The process typically takes 5–10 working days and is handled entirely by the providers. During the porting window, there is usually no interruption to service.

Staff Training

Modern VoIP systems are intuitive and require minimal training. Most employees adapt within a day or two. The main adjustment is learning the softphone interface on their computer or mobile, and understanding new features like presence indicators, instant messaging, and call transfer procedures. Any reputable VoIP provider will include onboarding training as part of the setup.

Choosing the Right Provider

Not all VoIP providers are created equal. When evaluating options, consider:

• Uptime guarantees — look for 99.99% or higher with a financially-backed SLA
• UK-based support — critical for timely issue resolution
• Data sovereignty — ensure call data and recordings are stored in UK data centres for GDPR compliance
• Integration capabilities — does it integrate with your CRM, helpdesk, or Microsoft 365 environment?
• Scalability — can you add or remove users instantly without contract renegotiation?
• Disaster recovery — what happens to your calls if the provider experiences an outage?
• Contract flexibility — monthly rolling terms are preferable to long lock-in periods

The PSTN Switch-Off: Why Now Is the Time

BT’s ongoing shutdown of the legacy Public Switched Telephone Network (PSTN) and ISDN services means that every UK business will need to move to an IP-based phone system by January 2027. Openreach has already stopped selling new ISDN and analogue lines, and exchanges across the country are being switched off in phases.

Businesses that migrate proactively can take their time to plan the transition properly, negotiate the best rates, and train staff without time pressure. Those who wait risk being forced into a rushed migration with less favourable terms and potential service disruptions during the changeover period.

Conclusion

The financial case for switching to VoIP is overwhelming for the vast majority of UK businesses. By eliminating line rental, slashing call charges, removing hardware and maintenance costs, and consolidating multiple communication services into a single platform, SMEs can typically reduce their telephony spend by 40–70% — savings that go straight to the bottom line.

Beyond the direct cost savings, VoIP delivers significant operational benefits: the flexibility to support remote and hybrid working, access to enterprise-grade features that were previously unaffordable for smaller businesses, and the ability to scale instantly as your business grows or contracts. With the PSTN switch-off making the transition inevitable, there has never been a better time to make the move.

The key is to approach the switch methodically. Audit your current telephony costs thoroughly, get detailed quotes from reputable providers, calculate your projected savings using the framework outlined in this guide, and choose a provider that offers transparent pricing, flexible contracts, and reliable UK-based support.

The businesses that act now will not only save money — they will gain a modern, flexible communications platform that positions them for growth in an increasingly connected world.