VoIP vs Traditional Landline: A Full Cost Comparison

For most UK businesses, VoIP costs less than a traditional landline once you count everything: line rental, call charges, handsets, maintenance and the cost of changing things later. A 10-person office on cloud VoIP can pay around £80 to £130 a month for unlimited UK calls and handsets, where the same office on landlines can pay more than that in line rental alone. The gap is widening because copper line rental is rising in the run-up to the PSTN switch-off. The exception is the cost VoIP adds that landlines don't: a decent internet connection and some form of power backup.

All prices below exclude VAT. Figures for VoIP come from the T2K system pages (October 2026). Landline figures come from published price lists and industry sources and are used as examples, so always check your own bills.

The quick answer

What does a landline really cost?

Landline costs come in layers, and the first one is the line itself.

Line rental. Every analogue line, ISDN2 line or ISDN30 channel carries a monthly rental. Copper rental is going up. One industry source reports basic copper line rental, including ISDN and extra lines on multiline setups, rising in steps from £19.95 a month to £23.95 in May 2026, £29.95 in August and £39.95 in October 2026. Prices vary by supplier and contract, so check your own bill, but the direction is clear.

ISDN channels. ISDN30 is charged per channel. As one example, KCOM's published list shows annual rental of £249 to £321 per ISDN30e channel from January 2026, depending on the care level, plus a one-off connection charge per channel. That's about £21 to £27 per channel per month before calls. A 10-channel ISDN30 therefore costs roughly £2,490 to £3,210 a year in rental alone. ISDN also costs more to install: our guide to business phone lines notes that installation commonly runs to several hundred pounds.

Call charges. On a landline you pay for calls separately, either per call or through a bundle. Calls to mobiles and some non-geographic numbers are usually the biggest cost. Gamma VoIP packages, by contrast, include unlimited UK landline and mobile calls under a fair usage policy.

The phone system on site. Most landline offices also run a PBX or key system. That means hardware to buy, a support contract to keep it covered and an engineer to change anything. Our blog on whether it's time to ditch your ISDN phone system covers the signs.

Repairs and changes. Faults on copper lines can take days to fix. Adding a number, moving a desk or setting up call forwarding often needs an engineer.

What does VoIP really cost?

VoIP pricing is simpler, but not free of extras. These are the published per-user prices on the T2K system pages:

Our full guide to how much a business phone system costs in 2026 breaks down each package, and the blog on Gamma Horizon pricing goes deeper on that platform.

The extra costs VoIP adds, and landlines don't, are:

• A reliable internet connection. Often you already pay for one. If you need an upgrade, see FTTP vs a leased line and what internet speed you need.
• Power backup. A small UPS keeps the router and switch running. Old copper lines carried their own power, which is a genuine advantage that VoIP has to replace. See what happens in a power cut.
• Network preparation. Usually minor. Our checklist for preparing your network shows what to check.

Worked example: a 10-person office

Here's an illustrative comparison. Treat the landline side as an example, because your own contract will differ. It assumes six analogue lines at about £30 a month each (the middle of the 2026 rental range above), or ten ISDN30 channels at KCOM's published rate.

Even before you add call charges and PBX maintenance to the landline side, the line rental alone costs more than a full cloud phone system. On Horizon Essential, the same office would save at least £600 a year on line rental, and usually far more once calls, support contracts and engineer visits are counted. Add internet and any extra handsets to the VoIP side for a fair comparison.

Where else does VoIP save money?

• Calls to mobiles. The biggest single saving for businesses that call customers and suppliers on mobile numbers.
• Staff changes. Adding a starter is a login, not an engineer visit. Our guide to how many handsets you can have on one VoIP system explains the limits.
• Office moves. Your numbers and settings stay in the cloud. See what happens to your VoIP system if you move office.
• Home and mobile working. Staff take calls on the app instead of paying for extra lines or diverts. See using your business phone system on a mobile.
• Missed calls. Auto attendants, queues and routing mean fewer lost enquiries. The blog on call routing, auto attendants and IVR shows how.
• Fewer suppliers. One bill for lines, calls and the system replaces several.

For a structured way to put numbers on this, see how to calculate VoIP ROI and 9 ways VoIP saves your business money.

What about the PSTN switch-off?

This is the cost most comparisons miss. The UK's traditional phone network is being retired, with the final switch-off date set for 31 January 2027 and providers already unable to sell new copper-based lines. Staying on a landline isn't a stable choice: it's a deferred migration, with rising rental in the meantime. Our guide to what happens if you don't migrate before the PSTN switch-off explains the consequences, and the 90-day PSTN switch-off checklist shows how to move in the right order. You can also use the PSTN switch-off checker, read about the big switch-off in 2027 and the BT ISDN switch-off, or ask what to do with an ISDN phone system.

If you want to keep a traditional-style connection for a time, a SIP trunk is the bridge. See what a SIP trunk is and analogue vs SIP vs VoIP.

Is there any case where a landline is cheaper?

Rarely, and only in narrow cases:

• A sole trader with a single line, low call volume and no need for features
• A site with no usable broadband at all, where a mobile signal is the only option
• Devices that still depend on a phone line, such as some alarms, lift phones and card machines, though most of these now have digital alternatives. Our PSTN checklist covers what to replace.

Even then, a mobile-based or app-only VoIP service often matches the price. Be honest about reliability too: landlines have a real strength during a power cut, and VoIP depends on your internet. That's easy to solve with a backup connection and a UPS. See what happens when your internet goes down and how to set up failover.

Will you keep your numbers?

Yes, in most cases. Switching to VoIP doesn't mean new phone numbers. See what happens to your number when you switch provider and how long porting takes. Phoneline+ retains numbers free on 12, 24 and 36-month terms. For local numbers see 01202 Bournemouth and 023 Southampton.

How to compare your own costs

1. Pull your last three phone bills. Add up line rental, calls, maintenance contracts and any one-off engineer charges.
2. List every line and what it does. Include alarms, lifts, card machines and fax.
3. Count real users. Not every line needs a handset.
4. Price the VoIP side properly. Include internet, backup and handsets. Use our phone system finder to shortlist.
5. Check your contract end dates. Early termination can change the timing, not the decision.
6. Avoid avoidable mistakes. Our guide to common VoIP installation mistakes shows what to watch for.

If you're in Dorset or Hampshire, T2K can compare your current bills against VoIP for offices in Bournemouth, Poole, Christchurch, Southampton and Portsmouth.

Frequently asked questions

Is VoIP cheaper than a landline? In most cases, yes. VoIP removes separate line rental, usually includes UK calls and avoids on-site PBX maintenance. The main added costs are internet and power backup.

How much does a business landline cost per month? It depends on the supplier and contract, but copper line rental is rising through 2026 and ISDN channels cost roughly £21 to £27 each per month on one published price list, before calls. Check your own bill.

Do VoIP calls cost less than landline calls? Typically, yes. Gamma packages include unlimited UK landline and mobile calls under a fair usage policy, so the biggest savings come on mobile calls.

What is the cost of installing VoIP compared with a landline? ISDN installs often cost several hundred pounds. Simple cloud VoIP systems often have little or no installation fee, though larger or multi-site installs, cabling and surveys may be charged.

Will I need to pay for both while I switch? Briefly, yes. Keep the old lines live until your numbers have ported and you've tested calls. See number porting rejected if a port stalls.

Does VoIP work without a landline? Yes. VoIP runs over your internet connection, so you don't need a landline at all. Broadband itself is increasingly delivered over fibre rather than copper.

What happens to my landline when the PSTN is switched off? Traditional analogue and ISDN lines stop working, so any phone, alarm or device relying on them has to move to a digital service.

Is a landline more reliable than VoIP? Old copper lines kept working in a power cut. VoIP needs power and internet, but a UPS and a backup connection close the gap. Faults on copper lines can also take days to repair.

The cheapest phone system is the one you don't have to replace twice. Request a quote and T2K will compare your current phone bills against a VoIP system, or use our phone system finder to see which systems fit first.