Best business phone line providers in the UK

Many of you will have landed here looking to find out who are the best business phone line providers, so here is a quick rundown of who we believe are currently out in front in a league of their own:

  1. T2k
  2. Gamma
  3. Kcom
  4. 4Com
  5. Lily Comms
  6. Reach Digital
  7. Spitfire
  8. Ring Central
  9. XLN
  10. Vodafone
  11. BT
  12. Plusnet
  13. Virgin Media
  14. Vodafone
  15. Zen
  16. O2
  17. Toople
  18. Woav

Business landline contracts

All business landline contracts, be that ISDN, PSTN or VoIP, will incentivise you to sign up for a longer-term agreement. It’s often in everyone’s best interest to have a longer deal as it means that all parties have the continuity of knowing the service will be in place for that period. 

You can, of course, choose to have a shorter contract, as a reasonable number of our customers do, but what you gain in flexibility, you lose in discounts and service continuity.

What is right for you and your business will, of course, be unique, so when you speak with your T2k account manager, be sure to raise the topic of contract length so you can discuss what is best for you.

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Glossary of business telecoms terms

Business telecoms is a field dominated by acronyms and jargon, so we’ve created this next section to help you navigate our world as best as possible. Remember, if you have any questions and want to speak to a telecoms expert, please get in touch via phone or using the live chat feature of our website.

Glossary of terms code:
Acronym / Word Technical Description Plain English Description
Analogue lines 2-wire copper telephone line Analogue telephone lines are the traditional phone lines that many people will have at home. These lines can only support one phone number and are often used for internet connectivity.
VoIP Voice over internet protocol  The underlying technology used to allow phone calls to be made over the internet. 

SIP

Session initiation protocol SIP, often called SIP trunks in telecoms, is a technology used for the transfer of media, such as phone calls.

IP Address

Internet protocol address The addresses computers and other devices are given on both the internet and on local networks.

Ethernet

Wired computer networking A group of devices and cables that are used to create local networks.

WiFi

Wireless fidelity

Wireless computer networking often used to describe wireless internet, but Wifi can also be used for networks that aren't internet-enabled.

ISDN Integrated services digital network A type of business telephone line that allows for multiple calls to take place at the same time over the same cable.

PSTN

Public switched telephone network The traditional telephone network which provides many of us with a landline at home. 

Cloud / Hosted

Hardware and software as a service  Computer systems and software that are located in internet-connected datacentres. The services these cloud systems provide are typically then rented, rather than bought outright.
Connectivity All types of internet connections Any connection to the internet, be that wireless or wired would be classed as connectivity. 
ADSL  Asymmetric digital subscriber line An internet service provided over your copper telephone line that is faster than dial-up technologies, but slower than fibre.

 FTTC

Fibre to the cabinet  An internet connection where fibre runs all the way to your local green telecoms cabinet, with only the final distance being copper. These connections are therefore much faster than ADSL. 
FTTP Fibre to the premises   A fibre cable between your office and the local telephone exchange. FTTP is currently being rolled out across the UK.
Leased Line 1:1 fibre connection A dedicated business-grade fibre internet connection typically used by companies that rely heavily on the internet and are of at least 10 employees and bigger.

What are business phone lines?

A business phone line is simply a landline used by a company rather than a domestic property. There are several different business lines to choose from, but with traditional PSTN and ISDN technologies being phased out by BT, most businesses are now switching to VoIP. 

If you want to know more about the latest technology, be sure to check out another of our recent guides titled “What is VoIP?” where we explain everything you need to know about it.

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PSTN landlines

PSTN landline is what many people in the UK will think of when you say “phone line”. The public switch phone network to give it its full name was introduced in the 1800s and has been the foundation of UK communications ever since. Businesses have used PSTN services as their primary method of transmitting telephone calls and faxes for many years, with the network being re-purposed in recent times and used for internet access. 

Millions of people and indeed businesses continue to use and rely on the UK’s PSTN some 140 years after it was first introduced, so the fact it is being turned off soon is nothing short of historic. As we will get into later in this guide, all businesses and consumers will need to move to another type of phone service before the big switch off; most expected to use VoIP via a cloud-based phone system such as our Horizon platform.

ISDN Landlines

ISDN or integrated services digital network is a business telephone service that allows for the simultaneous transmission of voice, data and video on the digitalised circuits of the PSTN. First introduced to the UK on June 25th 1985, it was initially called Integrated Digital Access (IDA). It was used to extend the digital phone network to customer premises, allowing for faster data transmission than traditional analogue lines. In the mid to late ’90s, ISDN (ISDN2) was used by schools, businesses and other organisations to achieve faster internet speeds. At the time, most analogue dial-up connections would give you between 28kbits/sec to 33.6kbits/sec, whereas a single ISDN channel was up to twice as fast. Another significant benefit of ISDN over analogue lines for internet access was that a connection could be made quietly and in just 1 second. Compare that to dial-up modems, which would be screaming at you for 10-15 seconds; it was an altogether more pleasant experience.

Over time and as technologies developed and ADSL was rolled out, businesses looked to use ISDN primarily for phone services, as it allowed for many more concurrent calls over a single line.

ISDN2 and ISDN2e

ISDN2 is the lower capacity version of ISDN, which is capable of handling two phone calls simultaneously. Often the best choice for small businesses, it can also be upgraded to support 60 concurrent calls. One of the most significant benefits of ISDN and ISDN2 is that you can use a range of numbers (DDIs) to have multiple phone numbers connected to the same physical line.

Benefits of ISDN2

  • Capacity - ISDN2 lines can handle two calls at the same time.
  • Scalability - ISDN2 can be expanded to support up to 60 channels.
  • DDIs - ISDN lines support number ranges, so you and your team can have your phone number (DDI).

While there are undoubtedly significant benefits of ISDN for businesses, it’s not without its disadvantages.

Disadvantages of ISDN2

  • Expensive to install - ISDN lines are complex and often costly to install, costing several hundred pounds. Not only that, installation typically takes several weeks. 
  • Line costs - ISDN is charged on a per-channel, and with each costing a similar amount to a PSTN line, the costs can quickly add up.
  • Equipment costs - ISDN lines require a PBX or router with a BRI card installed to work, which means you can’t simply plug handsets into the service.
  • Maintenance of equipment - Once you invest in a business phone system, you’ll want to make sure that it’s well looked after, so you’ll need a service contract with a telecoms company such as ourselves. 

Despite the higher costs, ISDN and ISDN2e are still widely used by many businesses, although many are now switching to VoIP

ISDN30

ISDN30 is the next step up from ISDN2, with the most notable difference being the number of channels you can scale up to. ISDN2 tops out at 60 channels, ISDN30 supports eight at the lower end, with each line capable of having 30 voice channels. I know 30 is half of 60, so how is ISDN30 capable of more? Unlike ISDN2, ISDN30 lines can be bonded so that you can have multiple ISDN30 lines going into the same phone system. Not only can ISDN be used for phone calls, but the data capacity allows for very high-quality video calls and even site to site communications. It’s perhaps easy to see why ISDN30 has been the connection of choice for larger businesses for some 20 years. 

Benefits of ISDN 30

  • Hugely scalable - bond lines together to scale your channel capacity.
  • High data transfer rates - use ISDN to host high-quality video conferencing and transfer large amounts of data.
  • Reliability - ISDN30 business services are robust and typically come with very high SLAs, meaning should you get any issues, they’ll generally be resolved promptly.

VoIP Phone Service

A VoIP phone service allows you to make and receive calls over the internet, rather than the old PSTN and ISDN networks. There are a few ways you can start using VoIP, which is best for your business will depend on your requirements.  

How can my business get VoIP?

  1. Your existing phone system may already be VoIP compatible, or it might be possible to install new components to upgrade it to VoIP. In some cases, your current office handsets can even be used, removing the need to replace everything, so it pays to speak to a telecoms company, such as ourselves, before making any decisions. At T2k, we have nearly 30-years of experience installing and supporting business telephone systems and today; we work with a wide variety of technologies, including VoIP. 
  2. For businesses with a significant number of people at a single site, and even those spread across multiple locations, it can be more cost-effective to buy a VoIP phone system than subscribing to a hosted service such as that mentioned in option three. One thing to bear in mind with both using an existing system or installing a new one, you’ll need several SIP trunks from your phone system provider, which will enable you to make calls over the internet. 
  3. The final option is to subscribe to a hosted VoIP system, like our own Horizon platform. A cloud VoIP system is provided to you as a service rather than buying and owning any equipment. This gives you access to many features, excellent reliability and room to grow, all for a predictable ongoing subscription fee. Businesses of all sizes can benefit from a hosted VoIP service. With many employers and employees moving towards flexible working, having your phone system located in the cloud rather than your office gives you the adaptability you need.

Benefits of VoIP

Far from being merely a replacement for PSTN and ISDN services when BT turns those off in 2025, VoIP, like many other internet-based technologies, brings a diverse set of benefits to businesses, including:

  • Reduced call costs - significant savings on both domestic and international calls
  • Advanced features - such as call recording, auto attendant and time of day routing
  • Better CRM integration - works with your favourite tools, moving you towards Unified Communications.
  • Excellent handsets and headsets
  • Softphones that allow you to turn your computer into a handset
  • Better call quality - HD calls and crystal clear quality.
  • Future proof - the latest technology
  • Scalable - scale your service up and down as required
  • Flexible - work from anywhere as long as you have an internet connection.

Why businesses are turning to T2k

With many companies to choose from for your telecoms, it can be somewhat challenging to determine which is best for your business. While we are, of course, biased, we think that for many companies, you’d be hard pushed to find a company better suited than us. Here’s why

About us and our services

T2k has been providing telephony services, including business phone lines, for nearly 30 years. We’ve built up a loyal customer base of companies that value excellence in customer service and want on-demand tech advice tailored to their business during that time. Many of our customers have been for over a decade, with a good number with us for much longer than that. We should point out that we’re not a substantial international business; we’re a small team of telecoms experts that work together to provide a service that is hard to beat. From our offices in Dorset, our sales, customer service, and technical teams look after a broad range of setups, from traditional and onsite VoIP phone systems through to cloud-hosted VoIP and connectivity, 

Why T2k:

  • Nearly 30 years of experience working with businesses like yours.
  • Not a big faceless organisation, we’re real people who would be more than happy to meet you for a coffee.
  • Continuity of staff, many of our team, have been with us for over 20 years, so you will always be speaking to someone who knows about your business systems.
  • Competitive pricing owing to long-standing relationships with all of the significant providers.
  • A one-stop-shop, we can provide everything from your handsets and softphones through to your phone system and VoIP numbers

FAQs

How do I get a business phone line?

The easiest way to get a business phone line is to contact an independent telecoms provider like ourselves to help work out what type of service best suits your company's needs.

Our technical account managers will take the time to find out about your business today and your plans for future growth before giving you tailored recommendations.

What are business phone lines?

Business phone lines are typically one of three types of service; PSTN (the same as many home services); ISDN (a business service that allows for more calls over the same line); or VoIP (calls over the internet).

With PSTN and ISDN networks being switched off in 2025, all businesses and consumers that want to keep a landline will need to move to VoIP.

Should my business have a landline?

Not all businesses need a landline, but for some, it's a necessity. If your business is primarily mobile and you don't have a fixed location, you can perhaps get away with not having one. However, if you want to provide your clients with a single number to reach multiple people at your company, along with having things like shared voicemail, call recording or more, then having a business landline is probably an excellent way to go.

As an independent telecoms company, we can give you non-biased advice on what would be best for your company, be that a mobile phone, VoIP services or perhaps even something different.

Can I use my landline for business?

If you have a landline at home, you could choose to use it for your business. However, you should be aware that doing will effectively make your home number publically available on the internet via your website and business directories. Another consideration is that should you ever open an office, transferring the number could be problematic, as by doing so, you could disconnect your home broadband.

In our opinion, a more straightforward solution is to get a hosted VoIP phone service, as it won't be tied to your home, nor will it impact your privacy at home. What's more, most cloud-based services are provided on a per-user, per-month basis, making them cost-effective and affordable.

How many phone lines does my business need?

When you're looking at phone lines, give some thought as to how many calls you and your team need to make at the same time. If, for instance, you anticipate having a maximum of four calls simultaneously, then you would need either four ISDN channels or four channels on your SIP trunk. 

With hosted VoIP services, you don't need to think about how many lines you need as the service is provided on a per-user, per-month basis, so it doesn't matter how many active calls you and your make or receive.

Who has the best business phone plan?

There are many business phone providers, but we believe T2k are the best, owing to our competitive prices, excellent customer support and outstanding track record. Indeed, many of our customers have been with us for over 20 years, due to the service they receive.

Are business phone lines more expensive?

Business phone lines such as ISDN will be more expensive than PSTN services you most likely use at home. However, the latest technology that businesses are moving to, VoIP, the prices are comparable and, in some cases, even less than what you pay at home.