In short
VoIP vs landline comes down to how calls travel. A landline carries calls over a copper line from the exchange to one building. VoIP carries them as data over your internet connection, so numbers and features follow your people to desk phones, apps and mobiles. Openreach says all traditional phone lines go digital on 31 January 2027.
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The basic difference
A landline is a physical line from the telephone exchange to your premises. An analogue line carries one call at a time; ISDN delivers several channels for a phone system. The number belongs to that line, so calls ring where the copper ends: on the desk or the switchboard in that building.
VoIP (voice over IP) turns speech into small packets of data and sends them over an IP network, usually your broadband or leased line. A codec compresses the audio, SIP sets up and ends each call, and RTP carries the sound. Your numbers live on a phone system rather than on a line, so a call can ring a desk phone in the office, an app on a laptop at home and a mobile at the same time. We explain the mechanism step by step in how a VoIP phone system works, and the protocols in SIP vs VoIP.
Most businesses do not buy "VoIP" on its own. They buy a VoIP phone system: extensions, groups, menus, voicemail and apps, with VoIP as the transport underneath.
VoIP vs landline comparison
| Traditional landline (analogue or ISDN) | VoIP | |
|---|---|---|
| How calls travel | Over a copper line from the exchange to one building | As data packets over your internet connection |
| Phone numbers | Tied to the physical line and the address it serves | Held on the phone system, so they move with you; existing numbers can usually be ported |
| Capacity | One call per analogue line; ISDN by channel, so more calls means more lines | Set by your licence or simultaneous-call limit and your bandwidth, so you add users without new cabling |
| Features | Basic on the line itself; anything more comes from an on-site PBX | Transfers, hunt groups, queues, menus, voicemail to email, recording and reporting, depending on platform and tier |
| Mobility and home working | Calls ring in one building | Desk phones, softphones and mobile apps ring wherever people sign in |
| Adding users or sites | New lines, wiring and often PBX hardware | Add users and sites on the same system |
| Power cut | A basic corded phone on an analogue line draws power from the line | Needs power for the router, network and phones; battery or UPS backup keeps calls going |
| Alarms and special lines | Designed for analogue lines | Each device needs a compatibility check, an adapter or an alternative |
| Cost model | Line rental per line or channel, call charges and PBX maintenance | Per-user or per-system licences, calls and numbers, handsets, connectivity and set-up |
| After 31 January 2027 | Traditional lines go digital; Openreach says ISDN services not migrated to IP will be ceased | Already digital, so ready for the switch-off |
For a deeper look at what a digital line on its own looks like (one number, one phone, delivered over broadband), see what is a VoIP landline?
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Tell us what matters most to you and we will recommend one, with the trade-offs explained.
Pros and cons of a landline
Landlines earned their reputation for simplicity, and it is worth being clear about what they do well before you move.
Strengths
- Simple: plug in a phone and it works, with nothing to configure
- A basic corded phone on an analogue line keeps working in a local power cut, because the line carries its own power
- Analogue devices such as alarms, franking machines and older door entry panels were built for it
Limitations
- Calls are tied to one building, so home and hybrid working depends on diverts
- More calls means more lines or ISDN channels, and more wiring
- Features depend on an on-site PBX, which needs maintenance and eventually replacement
- The network is being retired: Openreach says all traditional phone lines go digital on 31 January 2027
Pros and cons of VoIP
VoIP is where business calling is heading, and it brings real gains. It also has a few practical requirements, and we can plan for each of them with you during set-up.
Strengths
- Numbers and calls follow people to desk phones, apps and mobiles
- Rich call handling as standard on most platforms: hunt groups, queues, menus, voicemail to email and reporting
- Scale up or down by adding or removing users, with no new lines
- Several sites and home workers on one system, with internal calls between them
- Integrations with Microsoft 365, CRM systems and call recording, depending on the platform
What to plan for
- A suitable connection: enough upload bandwidth and a network that prioritises voice. Our VoIP requirements checklist covers broadband, QoS and Wi-Fi.
- Power: Openreach notes that digital phone lines rely on power and broadband, so plan battery or UPS backup for the router, switches and key phones.
- Analogue devices: alarms, lifts, door entry and card terminals each need a check, an adapter or an alternative.
- Emergency calls: make sure each number has the correct registered address, including for home workers.
Weighing up the options?
We can compare them against your own requirements and recommend what fits.
VoIP vs landline cost: what you pay for
A fair VoIP cost comparison against a landline looks at the whole bill, not just line rental against a licence.
| Cost element | Landline | VoIP phone system |
|---|---|---|
| The service | Line rental per analogue line or ISDN channel | Per-user subscriptions for Teams Phone, Webex Calling, Forever UC and Forever Teams; one annual licence per system, sized by simultaneous calls, for 3CX's commercial editions |
| Calls | Call charges on the line | Call bundles or call charges, depending on the platform and the route to the phone network |
| Phone system | An on-site PBX, its maintenance and eventual replacement | Included in hosted platforms; with your own PBX, its licence and support |
| Handsets | Analogue or system phones | Desk and DECT handsets can be bought outright or, in some cases, included in your monthly rental; many users need only an app |
| Connectivity | The copper line | Business broadband or a leased line with enough upload for your busiest hour |
| Set-up | Line installation and PBX programming | Number porting, call flows, provisioning and training |
Which works out better depends on how many lines and users you have, how many calls you make and what your current PBX costs to keep running. Our VoIP phone system cost guide explains each cost driver in more detail, and for your own figures, ask us for a quote.
Is VoIP better than landline for your business?
For most organisations moving off traditional lines, a VoIP phone system is the natural replacement, and it tends to suit you particularly well if:
- People work from home, several offices or on the road
- You use Microsoft 365 and want calls inside Teams
- Callers need queues, menus or out-of-hours routing
- You want to grow or shrink without adding lines
- You are on ISDN or an ageing PBX that needs replacing anyway
A single digital line can be enough for a very small site with one phone and nothing else connected, such as a kiosk or a lift. For anything with more than a couple of users, a phone system gives you much more for the move. See VoIP phone system for small business for options aimed at smaller teams, and best VoIP phone system for how to choose between platforms.
What happens to landlines in January 2027
Openreach says: "On 31 January 2027, all traditional phone lines will be going digital." Its business guidance adds that all services supported by ISDN need to be migrated to an IP service by January 2027, or the service will be ceased. Lines that have not moved may be placed on a temporary emergency voice-only service (EVAc), which Openreach says may not support the features you use today.
Digital phone lines usually work through a broadband router rather than a wall socket. Openreach advises checking any equipment connected to a phone line, including alarm systems, CCTV, payment card terminals, door entry systems, lift emergency phones and fire alarm monitoring. Our sister site covers the dates and the detail in its PSTN switch-off UK guide, and its alarm and special lines checklist covers those devices.
Ready to plan the move? Our step-by-step guide to switching from landline to VoIP covers the audit, numbers, devices and go-live.
How we help
Forever Systems supplies several VoIP platforms, so we match the platform to how you work instead of fitting you to one product: hosted 3CX, Microsoft Teams Phone, Webex Calling, Forever UC, Forever Teams and SIP trunks for phone systems you keep. Our guides to 3CX VoIP, Teams VoIP and Webex VoIP explain the main platforms. BT Cloud Voice is available from our sister company Forever Communications at cloudvoice.cloud.
We can audit your current lines and devices, check your connection, port your numbers, provision handsets and apps, and train your team. Much of the set-up can be done remotely; see VoIP phone system installation for how it runs.
Contact us with the number of lines, users and sites you have, and we can compare your current set-up with a move to VoIP, platform by platform.
How Forever Systems helps you choose a VoIP phone system
We supply and support several VoIP platforms, so we can recommend the one that fits how your team takes calls rather than fitting your business around one product.
- Platform advice across hosted 3CX, Microsoft Teams Phone, Webex Calling, Forever UC and Forever Teams, with SIP trunks for phone systems you already own
- A requirements check of your broadband, network and routers before anything goes live
- Numbers and porting: we can help you keep your existing business numbers and plan the move away from analogue and ISDN lines
- Handsets and headsets that suit each platform, bought outright or, in some cases, included in your monthly rental, with the options confirmed at quote
- Set-up and changes: call flows, users and devices configured for you, and help with moves, adds and changes afterwards
- For BT Cloud Voice, see our sister site cloudvoice.cloud, and for hosted and cloud platforms in depth, cloudphone.cloud
We work with businesses, schools, charities and public sector organisations.
Frequently asked questions
Is VoIP better than a landline?
For most businesses, yes: VoIP lets calls follow people to desk phones, apps and mobiles, adds call handling such as queues and menus, and scales without new lines. It needs a suitable internet connection and power backup. With traditional lines going digital on 31 January 2027, a move is needed anyway.
Is VoIP cheaper than a landline?
It can be, once you count everything: line rental, call charges and PBX maintenance on one side, and licences, calls, handsets and connectivity on the other. The answer depends on your users, lines and call volumes, so ask us for a quote that compares both.
Can I keep my landline number if I switch to VoIP?
Usually, yes. Geographic and non-geographic numbers can normally be ported to a VoIP phone system, including ISDN number ranges. The new provider requests the port from your current one using a letter of authority, and account details must match.
Does VoIP work in a power cut?
Not without backup power. Openreach notes that digital phone lines rely on power and broadband. A UPS for the router, network switches and key phones keeps calls going, and mobile apps carry on over mobile data. If anyone relies on a landline, tell your provider, who can offer battery backup.
Will landlines stop working in 2027?
Openreach says all traditional phone lines will be going digital on 31 January 2027, and that ISDN services not migrated to IP by then will be ceased. Digital lines usually work through a broadband router, so plan your move and check any connected devices early.
Is VoIP call quality as good as a landline?
It can be, and wideband (HD voice) codecs can sound clearer than a traditional line, provided the connection has enough upload bandwidth and the network prioritises voice. Our VoIP call quality guide explains the causes of poor audio and how to fix them.
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