Does a one-person business need a phone system? The UK arithmetic

For most one-person businesses in the UK, no — but the margin is thinner than in the US. A SIM-only plan at £10 a month plus Voipfone's 100-minute business line at £5 ex-VAT comes to roughly £16 a month all-in, and UK seat prices start low enough that the full phone-system seat is only a few pounds behind.

What settles it is not the seat price but the features: the moment you need an auto-attendant, recording, or a second person on the line, the seat wins. Until then the SIM-plus-line stack is cheaper and simpler.

This is the UK companion to the US version of this question, and one warning from why UK and US prices are not comparable applies before any number below: the two halves of this page's arithmetic are quoted on different VAT bases, and adding them without converting one is how most published comparisons in this category go wrong.

The VAT trap in this specific comparison

Because this page adds a consumer price to a business price, the 20% problem sits right in the middle of the sum. Consumer SIM deals are advertised as the price you pay — Lebara's pages print £10 with no VAT annotation, because the consumer price is the final price. Business VoIP pages mostly do the opposite: bOnline marks its prices "+vat", Voipfone's business page states "All prices exclusive of VAT", and Vonage UK's pricing page states "All prices exclude VAT unless otherwise stated" (all checked 2026-08-21, rows in the data file).

So the honest one-person sum is: SIM price as printed, plus VoIP price × 1.2. Voipfone's £5 plan is £6 as paid; bOnline's £13.95 unlimited-calling seat is £16.74 as paid. Every total below does this.

What the SIM half costs

Two carriers were on our check list for 2026-09-01, and they make an instructive pair, because one publishes and one does not — the same split who publishes a price documents across the phone-system market.

Lebara publishes everything. The deals index advertises SIM-only from £5 a month, and the product pages carry full terms: the 30GB plan is £10 a month, no contract, unlimited UK minutes and texts, 100 international minutes, EU and India roaming included. The index also lists 20GB at £10, 50GB at £15, an Unlimited plan at £25 on a 30-day basis or £22.50 on a 12-month plan, and a 30GB annual plan at £9 a month. Checked 2026-09-01 on lebara.co.uk.

Tesco Mobile publishes terms but its SIM-only price menu did not render for our tooling, so no figure appears here — the same "not readable" verdict some phone-system providers get in the main table, and recorded the same way rather than filled in from a review site. What the readable pages do state: SIM-only contracts run 12 or 24 months with unlimited minutes and texts, Clubcard Prices are frozen during the minimum term, and — a sentence worth quoting in full — "An annual increase to this price each April will only apply once your minimum contract period ends." That last clause is a fee-timing disclosure of exactly the kind this site exists to surface: the printed price is a minimum-term price, and the April rise mechanism is waiting behind it.

What the line half costs

£5 to £14 a month ex-VAT, on published UK prices. Voipfone's business ladder starts at £5 for 100 minutes and tops out at £20 for unlimited UK landline and mobile calls; bOnline starts at £7 (100 outbound minutes, unlimited inbound) with unlimited calling at £13.95; Vonage UK's Express tier is £10 with unlimited inbound. All ex-VAT, all checked 2026-08-21, all with source URLs in the data file.

Note what this half already includes: these are not bare virtual numbers, they are full phone-system seats sold singly with no minimum. The US market separates the $10 number product from the $20-30 seat; the UK market's cheap seats are the number product. That is why the UK gap is thin.

The 36-month totals

£576 versus £628 — the gap over three years is about £52 on the cheapest sensible stacks. Lebara's 30GB SIM at £10 plus Voipfone 100 at £6 inc-VAT is £16 a month, £576 over 36 months. The same SIM plus bOnline's unlimited-calling seat at £16.74 inc-VAT is £26.74 a month, £963. Swap the seat down to bOnline's £7 starter (£8.40 inc-VAT) and the seat stack is £18.40 a month, £662 — call it £86 over the SIM-plus-Voipfone stack, for a product with an auto-attendant in it.

Those are small differences, and they are the point: in the UK the one-person question is not settled by price at all. Run your own seat count and market through the calculator; at one seat the answers cluster within a few pounds of each other.

When the seat is the right answer

Because the UK price gap is small, the feature triggers arrive sooner than the US ones — any one of these is enough:

Who this page is not for

This page is not for teams of two or more — the per-seat tables on the rest of this site are the right tool from the second seat onward. It is not for anyone comparing coverage, networks or handsets; the SIM rows above record prices and stated terms only. And it is not a VAT guide — the ex-VAT versus inc-VAT display problem has its own page, which anyone mixing consumer and business prices should read first.

Sources

Written by Kaz (pen name). Figures are copied from providers' published pricing pages on the dates shown. We have not used these products. Corrections: contact form.