Business Phone System Buyers Guide UK 2026: How to Choose

Choosing a business phone system in 2026 is very different from five years ago. The PSTN switch-off has eliminated traditional landlines from the equation — every new phone system is now cloud-based VoIP. The question is which type of VoIP system suits your business, and what to look out for when comparing providers.

Types of business phone system

Hosted VoIP / Cloud PBX

The most popular choice for UK businesses. Your phone system lives entirely in the cloud — no on-site hardware beyond the phones themselves. The provider manages everything: software updates, security, capacity, and uptime. You access it through IP phones, a desktop app, or a mobile app.

Best for: Most businesses of any size. Especially good for teams that work from multiple locations or need to add/remove users easily.

Examples: GoYap, Gamma Horizon, eve — Enterprise UCaaS, Altos

Microsoft Teams Phone

If your business already uses Microsoft 365 and Teams, adding phone calling through Teams is a natural fit. Calls happen inside the Teams interface — no separate app needed. Two routes: a direct routing plugin (no extra Microsoft licence) or Microsoft's own Calling Plan.

Best for: Businesses already on Microsoft 365 who want to consolidate their tools.

SIP trunking

If you have an existing on-site PBX (phone system hardware in your office) and want to keep it, SIP trunking replaces the ISDN lines with internet-based SIP trunks. Lower cost than replacing the whole system, but you're still maintaining on-site hardware.

Best for: Businesses with recent PBX investment they want to protect, or complex call routing that's hard to replicate in the cloud.

Six questions to ask before choosing

1. How many users do you need?

Business phone systems are almost always priced per user per month. Make sure you count everyone who needs a phone extension — including part-time staff and remote workers. Most hosted VoIP systems let you add or remove users instantly online, so you're not locked into a fixed user count.

2. Do you need desk phones, or will an app do?

Many businesses find that a smartphone or desktop app replaces the desk phone entirely — especially for teams that are mobile or work from home. If you need desk phones, check what hardware the platform supports. GoYap is virtually device agnostic (works with almost any IP phone). BT Cloud Voice is hardware-locked to BT-approved phones only.

3. What call bundle do you need?

Check what minutes are included with each plan. GoYap includes 2,500 landline + 2,500 mobile minutes per user. Gamma Horizon includes 2,000 landline + 2,000 mobile minutes. Teams-Ready UCaaS includes 500 UK minutes. If you make a lot of calls, a generous bundle saves money.

4. Do you need Microsoft Teams integration?

If your team uses Teams for messaging and video calls, check whether the phone system integrates with it. Several platforms offer Teams integration — meaning your phone calls show up in Teams and you can make calls from the Teams interface.

5. What contract term suits you?

Contracts range from 30-day rolling (maximum flexibility, slightly higher price) to 24 or 36 months (lower price, less flexibility). If you're confident in your user numbers and want the lowest price, a 24-month contract makes sense. If your team size is uncertain, start rolling and fix the contract later.

6. What support do you need?

Some platforms are self-service — you configure everything through an online portal. Others include setup and ongoing support. If you don't have an IT team, look for a provider that includes onboarding and configuration in the price.

Hosted vs on-premise — the most important decision

Before comparing individual platforms, every business needs to decide between a hosted (cloud-based) phone system and an on-premise system. This is the single most consequential decision in choosing a business phone system, and it's worth understanding the implications properly.

Hosted VoIP — how it works

With a hosted system, your phone system lives in a data centre managed by your provider. Your phones — whether desk phones, smartphone apps or desktop softphones — connect to that cloud platform over your broadband connection. There is no physical phone system hardware in your office beyond the handsets themselves.

On-premise IP PBX — how it works

With an on-premise system, a physical phone system server sits in your office or server room. Your phones connect to it locally. External calls go out via SIP trunks connected to your broadband line. You or your IT team are responsible for managing, maintaining and backing up the system.

Remote working and multi-site — where hosted wins

For businesses with remote workers or multiple sites, hosted VoIP has a fundamental advantage over on-premise systems.

With a hosted system, every user — whether in the main office, a branch office, at home or on the road — connects to the same cloud platform over the internet. Adding a remote worker is as simple as installing an app on their smartphone or laptop. Adding a new site requires no additional hardware at head office — the new site just connects to the same hosted platform. There is no concept of "being in the office" versus "being remote" — the system treats all users identically regardless of location.

With an on-premise system, remote working and multi-site connectivity requires additional configuration and hardware:

• Remote workers need either a VPN connection back to the office to reach the on-premise system, or a separate remote access solution configured by your IT team
• Multiple sites need either a dedicated network connection between sites (a leased line or MPLS circuit) or a VPN, plus routing configuration to allow calls to pass between the sites
• Both scenarios add complexity, cost and potential points of failure that simply don't exist with a hosted system

Resilience and failure — the critical difference

This is where the on-premise vs hosted decision has the most significant real-world implications, and where many businesses don't think through the consequences until something goes wrong.

What happens when a hosted system has a problem

If your broadband connection fails, your hosted phone system goes offline — but the platform itself continues running in the cloud. Calls can be automatically diverted to mobile numbers, so your business never stops receiving calls. When your broadband is restored, everything comes back instantly with no intervention needed.

The hosted platform itself is typically running across multiple redundant data centres. The provider's infrastructure failing is extremely unlikely — and if it does, the provider's engineers fix it, not yours.

What happens when an on-premise system has a problem

An on-premise system introduces multiple potential failure points that are entirely your responsibility:

• If the physical server fails — your phone system is down until it is repaired or replaced. This could take hours or days.
• If your broadband fails — all external calls stop. Unlike hosted, there is no automatic failover unless you have specifically configured and paid for one.
• If there is a fire, flood or break-in — your phone system may be destroyed entirely.

To make an on-premise system genuinely resilient, you need a complete backup system at a separate physical location — a second server at a different site configured to take over if the primary fails. This requires duplicate hardware, duplicate connectivity, and ongoing maintenance of both systems. For most SMEs, this cost and complexity is difficult to justify when hosted systems provide superior resilience at a lower overall cost.

When on-premise still makes sense

On-premise systems are not obsolete — there are specific scenarios where they remain the right choice:

• Large organisations with dedicated IT teams and existing on-premise infrastructure investment
• Businesses with regulatory requirements for on-site data processing or call recording storage
• Sites with very poor or unreliable internet connectivity where cloud dependence is a risk
• Highly customised call routing that cannot be replicated in available hosted platforms

For the vast majority of UK SMEs — particularly those with remote workers, multiple sites, or without dedicated IT resource — hosted VoIP delivers better resilience, lower total cost of ownership, and simpler management than an on-premise alternative.

Quick comparison of main platforms

Pre-purchase checklist

• ✓ Count all users — including part-time and remote staff
• ✓ List all features you currently use and can't live without
• ✓ Check your broadband is suitable for VoIP (we can test this)
• ✓ Decide whether you need desk phones or an app is sufficient
• ✓ Check compatibility with your existing IP phones if keeping them
• ✓ Allow 7–14 working days for number porting
• ✓ Check what happens to your alarm, fax and card terminal
• ✓ Compare 24-month vs rolling contract total cost