Business phone systems

Find the best phone system for your business, based in the cloud or on your premises

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Smart phone systems to suit every business

Finding the phone system best suited your business will help it thrive and grow. At BT, we’re ideally placed to deliver the perfect system for you. We can help you serve your customers better, enable effective collaboration, and support flexible working.

Whether you need a plug ’n’ play VoIP (Voice over Internet Protocol) handset to save money on calling, or a larger, cloud-based VoIP or on-premises system to power a large call centre, you’ll find the solution you need. And we’ll find you the most cost-effective system, with the flexibility to adapt for the future.

What type of system do you need?

Cloud-based VoIP systems

A VoIP virtual phone system makes calls over the internet, giving you real flexibility and streamlining your business communications. Whether your people are in the office, working from home, or out on site – they can all use it.

On-premises PBX systems

We'll install one of our top-flight PBX systems on your premises along with any PSTN or ISDN lines you may need. And with our PBX systems, VoIP and SIP trunking are also available.

Mobile-based systems

These act like a mobile and think like a phone system. Replace your desk phone and mobile with a single device that switches you seamlessly between the office and mobile networks. They're cloud-based for minimal on-premises equipment.

Compare cloud-based VoIP and on-premises phone systems
Popular products
Number of users
Ideal for
Call package option
Mobile device integration
Call management features
Audio conferencing
CRM integration
Online management portal
Cost - payment options
Virtual geographic numbers
Video conferencing
Call monitoring / recording

Cloud-based systems

Enjoy the flexibility of making calls over the internet

BT Cloud Phone
BT Cloud Voice

1 - 250+

Office, mobile workers, and home-office users

Inclusive, unlimited calls package - also includes bundle options






Inclusive maintenance

24/7* dedicated helpdesk

Automatic updates
Easy to add users
Simple relocation to new premises

Plug + play
(Engineer install option with BT Cloud Voice)

Cost per user
(Lease available for BT Cloud Voice)





On-premises systems

We’ll install all the lines and equipment you need on-site

Avaya IP Office

2 - 20,000

Flexible modern communications platform designed to meet the needs of SMBs

Via your network phone lines






3 maintenance options available

Fault reporting 24/7

Option to upgrade
Install new extensions

Engineer install

Purchase or lease

Via BT SIP Trunk


Upgrade option

Upgrade option

Mobile-based systems

A clever device that combines your desktop phone and your mobile

BT One Phone

5 - 500+

Managing all calls/voicemail on one mobile device

Unlimited calls option






Inclusive maintenance

Fault reporting 24/7

Automatic updates
Easy to add users
Simple relocation to new premises

Plug + play (Engineer install option with onsite network)

Cost per user





Why BT Business?

Local expertise

Get the right solution for your business from BT Local Business experts

Outstanding service

Unbeatable local knowledge, national resources, and personal service

The personal touch

We’ll get to know you and your business challenges

Industry leader

We’re the UK’s leading provider of phone systems


What are the main differences between an on-premises phone system and a VoIP system hosted in the cloud?

For many years the only solution was to have a phone system on your premises. This box of kit connects up all your phone extensions and links them to the phone network, often using PSTN or ISDN telephone lines. You may have seen the acronym PBX (it stands for Private Branch exchange): that’s another name for an on-premises phone system.

Typically, a phone system is a capital purchase with a one-off up-front cost, although you may be able to spread your payments through a leasing agreement. Some customers don’t feel that they’re ready for the cloud, and like to have the security of having the actual phone system located on their premises.

A cloud system, sometimes called a hosted phone system, uses the internet to connect all your extensions to each other and the public phone network. There is no actual physical phone system hardware on site (apart from the phones). The system itself is easy to set up (often with a plug ‘n’ play option).  You usually pay for each user on a monthly basis (at least you do with our cloud-based systems: BT Cloud Voice, BT Cloud Phone, and BT One Phone) so there are no significant up-front costs.

Now, there is a quasi-third option. You can sometimes link to VoIP services on an on-premises system. This hybrid gives you the reassuring presence of an on-premises system with the cost savings of being able to make calls over the internet (take a look at the Avaya IP Office).

Is the call quality the same on both types of system?

People who haven’t (knowingly) experienced it before sometimes tell us they’re concerned about the call quality of a cloud-based system. You don’t need to worry: with a cloud based system you'll get the same level of clarity as with a regular landline. In fact, depending on the set-up of your system, you may even get calls with high definition clarity.

And you’ve probably already used a cloud system without realising. As more and more businesses move towards cloud-based systems, it’d be a surprise if you hadn’t called a business that used one.

Which is the cheapest option?

A cloud-based system usually has a small set-up cost but you’ll need to buy handsets. These systems generally attract a monthly rental cost for each extension. So, with a high number of users over a lengthy period, the costs may well equate to the cost of an on-site system.

An on-site system generally has a higher up-front cost, as you have to buy the equipment. On the positive side, though, you can often lease the system to spread the costs.

So which is best for me?

As you might have gathered, there's no simple answer to this. Which is best depends on your business, your expectations and requirements, and of course, your internet connection!

For a small business with simple requirements and a stable internet connection, a hosted cloud-based solution offers low up-front costs and a manageable monthly fee. But you also have the choice of an on–premises system, if you prefer to have the actual hardware on your site.

Do I have to pay for a new system in one go?

No, you can spread your payments on a finance option with an on-premises system and also BT Cloud Voice (for handsets).

Can you come and see me at my premises to discuss which option is best?

At BT Business, we’ve got both types of phone systems and years of experience in helping businesses choose, install, and use them. We’ve got a network of telecommunications experts across the UK, which we call our BT Local Business partners. There’s one in your area.  

Just call us and we’ll discuss your options and, if we need to, we’ll visit you at your premises. That way we can see your business in action and recommend the set-up that’s best for you.