Guide
BT Digital Voice alternatives: keep your landline without broadband
BT Digital Voice is BT's replacement for the traditional copper landline: your calls move onto your broadband connection before the PSTN switch-off on 31 January 2027. For many households it's fine. But if your phone matters when the broadband is down, when the power is off, or at a property with no broadband at all, you have other options — and you can keep your number.
What's the best alternative to BT Digital Voice?
A landline that runs over the mobile network instead of broadband. ONSIM offers three: a Virtual Landline that rings your existing mobile (£5/mo), a Landline SIM that puts your number natively on a mobile (£10/mo), and a Landline Replacement box for your existing analogue handset. None needs broadband, an app, or BT.
What is BT Digital Voice?
Digital Voice is BT's VoIP home phone service. Instead of calls travelling over the copper telephone network, they travel over your BT broadband, with your handset plugged into the back of your BT router or paired with it wirelessly. It exists because the copper PSTN — the network behind every traditional landline — is being permanently switched off on 31 January 2027, affecting around 14 million lines.
To be fair to BT: on a solid broadband connection, Digital Voice call quality is good, it's typically bundled with your broadband package, and you keep your number. If you have reliable BT fibre and the phone is a convenience rather than a lifeline, it's a reasonable default.
Why people look for an alternative
- Broadband dependency. If your broadband goes down, your landline goes down with it. For a business, that's missed calls; for anyone relying on the phone, it's a real gap.
- Power cuts. The router needs mains power. No electricity means no phone, unless you qualify for BT's battery back-up (aimed at vulnerable customers).
- Call quality on busy broadband. VoIP shares your connection with everything else in the house. Congested or long-line broadband can mean choppy calls.
- No broadband at the premises. Some properties — second homes, rural addresses, lift lines, standalone alarm lines — simply don't have or want a broadband package.
- You're leaving BT anyway. The switch-off is a natural moment to shop around rather than accept the default migration letter.
Three alternatives that never touch your broadband
ONSIM has run landline numbers over the mobile network since 2013 — before the switch-off was announced. All three products below are unaffected by the PSTN switch-off, need no broadband, and can carry your existing number across.
Virtual Landline — £5/mo
Your 01, 02 or 03 number rings on your existing mobile. No new hardware, no SIM swap, no app — calls arrive through your phone's normal dialler. Includes up to 2,500 forwarding minutes a month under fair use. The simplest way to keep a landline number alive after the switch-off.
Best for: households and sole traders who mainly receive calls.
Landline SIM — £10/user/mo
A SIM or eSIM with your landline number natively on it. Inbound calls ring like any mobile call, and outbound calls display your landline number. Unlimited UK calls and SMS under fair use, voicemail, hold & transfer and VoLTE included.
Best for: businesses that make and take calls on the landline number.
Landline Replacement — launching
Keep your existing analogue handset. A small 4G box (an ATA) replaces the BT socket: unplug from the wall, plug into the box, carry on. Works with analogue phones, alarms and lifts. £10/mo + a one-off £79 box, or £18/mo with the box included.
Best for: anyone who wants the phone on the hall table to keep working as-is.
BT Digital Voice vs the ONSIM alternatives
All ONSIM prices ex VAT. Digital Voice terms vary by BT package — check yours before deciding.
| BT Digital Voice | ONSIM Virtual Landline | ONSIM Landline SIM | ONSIM Landline Replacement | |
|---|---|---|---|---|
| Works without broadband | No — calls run over BT broadband | Yes — mobile network | Yes — mobile network | Yes — 4G box |
| Works in a power cut at the phone end | No — router needs mains (battery back-up for vulnerable customers) | Yes — rings your mobile, which runs on its battery | Yes — rings your mobile, which runs on its battery | Box needs power — add a battery back-up if critical |
| Keeps your existing number | Yes | Yes — port-in covered | Yes — port-in covered | Yes — porting included |
| App required | No at home; app for calls away from the router | No | No | No |
| Keeps your existing analogue handset | Plugged into the router, yes | No — calls ring your mobile | No — calls ring your mobile | Yes — that's the whole point |
| Price | Typically bundled with BT broadband | £5/mo | From £10/user/mo | £10/mo + £79 box, or £18/mo |
Digital Voice is probably fine if…
- You already have reliable BT broadband and plan to keep it
- The landline is a convenience, not a lifeline or a business line
- You're happy with the handset living next to the router
- You have a mobile as a fallback for outages and power cuts
If that's you, accepting BT's migration is a legitimate choice. We'd rather say that plainly than pretend otherwise.
Choose an ONSIM alternative if…
- Missed calls cost you money — the line must survive broadband outages
- There's no broadband at the property, or you don't want to pay for one
- You want the number on a mobile, out of the house, with no app (Landline SIM)
- You have an analogue phone, alarm or lift line to keep alive (Landline Replacement)
- You want out of BT entirely but want to keep your number
Why is this happening at all?
The copper PSTN switches off on 31 January 2027. No new copper lines have been sold anywhere in the UK since September 2023, and Openreach already pushed the deadline back once from December 2025 — it isn't moving again. Digital Voice is BT's answer for its own customers; it is not the only answer. We've written up why BT is switching off landlines — including the commercial drivers that don't make it into the customer letters — and where the switch-off applies (spoiler: everywhere).
BT Digital Voice alternative FAQs
The questions people ask before deciding whether to accept BT's migration or move elsewhere.
Do I have to switch to BT Digital Voice?
No. Digital Voice is BT's default replacement for its own copper landline customers, but you are free to move your number to any provider you like. You can port your number to a mobile-network service such as an ONSIM Virtual Landline, a Landline SIM, or a Landline Replacement box instead.
What is BT Digital Voice, exactly?
It is BT's VoIP home phone service. Instead of your calls travelling over the copper telephone network, they travel over your BT broadband connection, with your handset plugged into (or paired with) your BT router. It replaces the traditional landline ahead of the PSTN switch-off on 31 January 2027.
What happens if my broadband goes down?
With Digital Voice, your landline goes down with it — the phone and the broadband are the same connection. A mobile-network landline keeps working because it never touches your broadband: calls to an ONSIM number ring on a mobile or through a 4G box regardless of what your router is doing.
Does Digital Voice work in a power cut?
Not on its own. The router needs mains power, so if your electricity goes off, so does your phone. BT offers battery back-up units to customers it classes as vulnerable, and a mobile phone can act as a fallback. With ONSIM, calls ring on your mobile, which runs on its own battery — the power cut at your house doesn't touch the mobile network.
Can I keep my number if I don't want Digital Voice?
Yes. Your 01, 02 or 03 number belongs with you, not with BT. ONSIM ports numbers in as standard (porting typically completes in 10–14 working days, and the port-in fee is covered). See how to keep your landline number.
Is BT Digital Voice any good?
For many households, yes. If you have reliable BT broadband, mainly use the phone casually, and don't depend on it for safety or business, Digital Voice is a perfectly sensible replacement and is typically bundled with your broadband package. This page exists for the people it doesn't suit — not to pretend it suits no one.
Do the ONSIM alternatives need an app?
No. That's the point. Virtual Landline forwards calls to your existing mobile using its normal dialler. Landline SIM puts the landline number natively on a SIM or eSIM. Landline Replacement plugs your existing analogue handset into a 4G box. No app, no softphone, no VoIP account.
What if there's no broadband at my property?
Then Digital Voice isn't really an option, since it requires a broadband line to carry calls. All three ONSIM products run over the mobile network, so a property with mobile signal but no broadband can keep a working landline number without buying a broadband package it doesn't otherwise need.
Can I keep using my existing handset?
With Digital Voice you plug your handset into the router (or use BT's own Digital Voice handsets). With ONSIM, Landline Replacement is the option built for this: your existing analogue phone plugs into a small 4G box and works as it always has — it also supports analogue alarms and lift lines.
How much do the alternatives cost?
Virtual Landline is £5/month + VAT. Landline SIM is from £10/user/month + VAT with unlimited UK calls under fair use. Landline Replacement is £10/month + VAT with a one-off £79 box, or £18/month with the box included on a 24-month contract.
Is Digital Voice the same as VoIP?
Yes — Digital Voice is BT's consumer brand for VoIP over its own broadband. Other providers have their own equivalents. If you want to understand the wider category, we've compared virtual landlines and VoIP in plain English.
When do I need to decide by?
The copper PSTN switches off on 31 January 2027, and no new copper lines have been sold anywhere in the UK since September 2023. Don't wait for the deadline — porting a number takes 10–14 working days, and the closer to the cut-off you leave it, the busier every provider will be. Check your line with our 2-minute switch-off checker.
Keep your landline. Skip the broadband dependency.
ONSIM has delivered landline numbers over the mobile network since 2013. Port your number in (fee covered), set up in minutes, and your landline stops caring what your broadband is doing.