Alternatives to a BT landline for business

If your business still uses a BT landline, you have three real alternatives: a hosted VoIP phone system, SIP trunking on your existing PBX, or a mobile-based service. All three work over the internet instead of the old copper network, which Openreach is switching off on 31 January 2027. Most small and medium businesses move to hosted VoIP, because it's the simplest option and needs no on-site hardware.

This guide explains each alternative honestly, including where it falls short, so you can choose the right one before the switch-off deadline rather than after it.

What's actually happening to BT landlines?

Openreach, not BT itself, is retiring the UK's old analogue phone network (PSTN) and the digital ISDN network that many business phone systems still run on. The deadline is 31 January 2027. After that date, calls can only travel over the internet.

BT is one of many providers using that Openreach network, so this affects every landline in the UK, not just BT customers. If you're a BT customer, BT's own answer is to move you to BT Digital Voice, which sends your existing number over your broadband line. That keeps things simple, but it's still worth comparing what else is available, because BT isn't always the cheapest or the most flexible option for a business.

Not sure whether you're affected yet? Use our PSTN switch-off checker, or read the full 2027 switch-off guide.

What are the alternatives to a BT landline?

Hosted VoIP: the simplest replacement for most businesses

A hosted VoIP system, sometimes called a cloud phone system, replaces your landline entirely. Your phone system lives with a provider rather than in a cupboard on site, and calls travel over your broadband connection. You can answer calls on a desk phone, a laptop or a mobile app, and staff can work from anywhere without losing calls.

This is the option most businesses end up choosing, because there's nothing to install and no ongoing hardware to maintain. It also comes with features a basic landline never had, such as call recording, an auto-attendant, and reporting on call volumes. Our guide to what hosted VoIP actually is covers how it works in more detail.

The trade-off is that it depends on your internet connection. If your broadband goes down, so does your phone line, unless you've planned for that. We cover how to stay connected to VoIP during a power or internet outage separately.

SIP trunking: keep your current phone system, change what it connects to

If you already have a PBX phone system you're happy with, and it only needs replacing because it currently runs over ISDN lines, SIP trunking might be the better fit. It replaces the ISDN lines feeding your system with an internet connection, so the phone system itself stays the same for your staff.

This suits businesses that have invested in a system, such as a 3CX deployment, and don't want to change how it's used day to day. Our guide to SIP trunking explains when it makes sense instead of moving to hosted VoIP.

Mobile-only: sometimes enough, rarely the full answer

Some sole traders and very small teams manage without a landline at all, using a business mobile number instead. It's the cheapest option, since there's no separate line to pay for, and it works anywhere there's mobile signal.

It usually falls short once a business needs more than one person answering the same number, or wants calls to go to voicemail professionally rather than to a personal mobile's default message. A landline replacement service, like Gamma Phoneline+, gives you that same simplicity with a proper business number and voicemail to email, while still working from a mobile app.

BT Digital Voice: staying with BT

BT's own replacement moves your existing landline service onto your broadband connection, using a compatible router. For a single line with light call handling, this can be the path of least resistance, particularly if you're already a BT broadband customer.

It's worth comparing the cost and features against independent providers before committing, because BT Digital Voice is built for replacing a single household or single-line landline. It doesn't offer the call routing, reporting or multi-user features a growing business is likely to need within a year or two.

Which alternative is right for your business?

The right choice depends mainly on how many people need to answer calls and how your team works.

• One person, or very light call volumes: Gamma Phoneline+ or BT Digital Voice usually cover it.
• A small team who need calls routed between them: hosted VoIP, such as Gamma Horizon.
• You already have a PBX you're happy with: SIP trunking keeps it running past the switch-off.
• Growing team, multiple sites, or CRM and Teams integration: a fuller hosted system such as 3CX or Gamma Webex.

We've written a full breakdown of which phone system suits which team size, with worked examples from a one-person business up to 250 staff. If you'd rather answer a few questions and get a ranked shortlist, the Phone System Finder does the comparison for you.

What do I need to check before switching?

Whichever alternative you choose, a few things are worth confirming first:

• Your broadband can handle it. VoIP call quality depends on a stable connection. Our guide to optimising quality of service for VoIP explains what to check.
• Anything else uses your phone line. Alarms, door entry systems and some card payment terminals sometimes rely on the old analogue line and may need separate attention.
• You can keep your number. Moving your existing number to a new provider is called porting, and it's usually straightforward. See our guide to transferring a PSTN number to VoIP.

Frequently asked questions

Do I have to switch before 2027?

Yes, if you want to keep a working phone line. Openreach is retiring the PSTN and ISDN networks on 31 January 2027, and no analogue or ISDN line will work after that date. Providers are encouraging businesses not to leave it until the final months, since demand for engineer visits increases closer to the deadline.

Will I lose my landline number if I switch away from BT?

No. In almost all cases you can move your existing number to a new provider, a process called porting. It doesn't usually involve any downtime if it's planned properly. See our guide to phone number porting.

Is VoIP more expensive than a BT landline?

Not usually. Hosted VoIP typically costs less per line than a traditional BT landline, and it includes features BT's basic landline never offered, such as voicemail to email and call routing. Our guide to VoIP savings and ROI shows how to work out the numbers for your business.

What happens to my landline if my broadband goes down?

Calls stop working until your connection is restored, unless you've set up a fallback such as call diversion to a mobile. This is worth planning for if your business can't afford to miss calls. Read more in our guide to VoIP during power and internet outages.

Do I need to buy new phones?

Not always. Many hosted VoIP systems work through a mobile or desktop app, so you may not need physical handsets at all. If you'd rather keep desk phones, most providers support standard VoIP-compatible handsets, and some will work with your existing ones.

Compare BT landline alternatives with T2K

T2K Voice & Data works independently of any one provider, so we'll tell you honestly which alternative fits your business, whether that's a BT product or not. Businesses from Bristol to Glasgow use the Phone System Finder to compare options in a few minutes, or you can get independent advice and talk it through directly.