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Quick answer (checked 22 September 2026): On 24-month terms, ex VAT, the four networks’ published unlimited-data business SIM prices are O2 £17.50, Three £19.17 (offer including Go Roam in Europe; list £28), EE £25 (Business Essential) and Vodafone £29.17 (100Mbps cap; a £19.17 promotion was running). “Unlimited” means unlimited in the UK on a phone: every network applies roaming fair-use limits (12GB to 60GB a month), and EE and Vodafone publish usage or speed conditions you should read before putting a SIM in a router.
Sources: EE Price Guide for Small Business v20.9, Vodafone Business, O2 Business Shop and Three Business websites. Request a dated multi-network quote.
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An unlimited-data business SIM removes the one thing finance teams hate most about mobile bills: out-of-bundle data charges. But the four UK networks define “unlimited” differently, price it very differently, and attach conditions on speed, roaming, tethering and router use that only show up in the price guide. This page compares the published business unlimited plans from EE, Vodafone, O2 and Three as they stand in September 2026, explains the small print, and sets out when a large capped allowance is the better buy.
This guide covers phone SIMs for staff handsets. For routers, MiFi units, site cabins and broadband failover you want a data-only plan — see our business mobile broadband page. For the whole SIM-only market, capped plans included, start with business SIM only deals.
Unlimited data business SIMs compared (24 months, ex VAT)
| Network / plan | Monthly price | Speed | UK usage conditions | Roaming | Annual rise |
|---|---|---|---|---|---|
| O2 Business Unlimited (Classic Business Plan) | £17.50 | 5G included | Fair usage policy applies | EU roaming included up to 25GB; charged beyond | £1.50 each 1 April |
| Three Business Unlimited + Go Roam in Europe | £19.17 offer to 14 Oct 2026 (was £28); £28 on 12 months; £32 rolling | Uncapped 5G | No UK fair-use cap; abnormal-use clause; Personal Hotspot included | 49 European destinations included; 12GB fair use; £5/£7 a day elsewhere | £0.75 (plans £10–£20) or £1.50 (over £20) each April |
| EE Business Essential Unlimited | £25 (24m); £27 (12m); £31 rolling | Uncapped 5G+; Network Boost priority | For your sole use; usage above 600GB a month may be deprioritised or moved to another plan; tethering included | £2.26 a day in Europe unless Roam Abroad added; 60GB fair use; max 3 months continuous | Fixed amount each 31 March |
| EE Business All Rounder Unlimited | £30 | As above | As above | Roam Abroad available as the Inclusive Extra (Europe + 7 destinations) | Fixed amount each 31 March |
| Vodafone Business Unlimited | £29.17 list; £19.17 promotion seen; £11.67 per extra SIM on Multibuy (5–9 SIMs) | Capped at 100Mbps | Acceptable use policy | None inclusive; 25GB fair use | £2.09 (sole trader) / £3.01 (Ltd) each 1 April |
| Vodafone Business Unlimited Plus / Premier | £36.67 / £40 | Uncapped 5G Ultra; Premier adds Speed Boost up to 2x | Acceptable use policy | Plus: 52 European destinations; Premier: 84 worldwide; 25GB fair use | £2.09 / £3.01 each 1 April |
Prices are the networks’ published small-business list prices on 22 September 2026. Three’s include its £5 recurring-payment discount; O2’s is for new customers paying by direct debit. Promotions on unlimited plans change monthly — the network guides below are updated when they do: EE, Vodafone, O2, Three.
What “unlimited” means on each network
- EE is the most explicit. Its unlimited plans are “for your sole use only”, and EE may treat usage above 600GB a month as excessive and deprioritise your traffic at busy times or move you to a more suitable plan. Below that, there is no cap and no speed restriction, and unlimited plans get Network Boost, which prioritises your data in congested locations.
- Vodafone caps the standard Unlimited plan at 100Mbps download; you pay for Unlimited Plus or Premier to remove it. All unlimited plans sit under Vodafone’s acceptable use policy.
- Three publishes no UK data or speed cap on business unlimited plans and includes Personal Hotspot. Its terms reserve the right to act on abnormal or commercial-scale use — in practice, running an office’s broadband off a phone SIM.
- O2 states that a fair usage policy applies and, for roaming, that unlimited customers are charged once they pass 25GB in its Europe Zone. Its Business Shop does not publish a UK usage threshold.
For a normal heavy user — video calls all day, cloud storage sync, tethering a laptop in the field — none of these conditions will bite. They exist to stop phone SIMs being used as fixed broadband.
Tethering and hotspot rules
EE lists tethering as included on all single-user business plans, and Three lists Personal Hotspot as included on every business plan. Vodafone’s and O2’s published small-business pages don’t state a tethering allowance for unlimited plans one way or the other, so check the plan terms on your quote. If a laptop will use the SIM as its main connection every day, a data-only SIM in a router or dongle is the cleaner solution: EE’s Business Mobile Broadband unlimited data plan is £34 a month rolling or £30–£38 on 12 months, and Three sells data-only SIMs alongside its phone plans.
Roaming with an unlimited business SIM
Unlimited never means unlimited abroad. Each network sets a monthly roaming fair-use allowance and, separately, decides whether roaming is included in the price:
| Network | Is EU roaming included? | Roaming fair-use allowance | Beyond Europe |
|---|---|---|---|
| EE | No: £2.26 a day, unless Roam Abroad (Inclusive Extra on All Rounder / Full Works, or £11.90 a month passport) | 60GB a month on unlimited plans; three months continuous maximum | Business Passport £9.32 a day / £46.61 a month (1GB a day / 10GB a month); World Passport £11.64 / £69.93 |
| Vodafone | Standard Unlimited: no. Plus: 52 European destinations. Premier: 84 worldwide | 25GB a month | Premier’s Xtra covers 84 destinations; otherwise daily charges apply |
| O2 | Yes, EU roaming included | 25GB a month in the Europe Zone | O2 Travel add-ons on quote |
| Three | Yes on the 24-month Unlimited + Go Roam in Europe plan (49 destinations); otherwise £2 a day | 12GB a month; extra charges possible if roaming 60+ days in any four months | Go Roam Around the World £5 a day, Around the World Extra £7 a day (waived on Boundless plans) |
If a user roams in Europe regularly, the cheapest genuinely unlimited-in-the-UK option with roaming built in is currently Three’s Go Roam plan, followed by EE All Rounder with Roam Abroad selected (£30) and Vodafone Unlimited Plus (£36.67). Our business data roaming guide goes deeper.
5G and 5G standalone on unlimited plans
- EE: every new business plan sold from 13 May 2026 includes 5G+, EE’s standalone 5G, which EE says covers over 70% of the UK population. Unlimited plans also carry Network Boost.
- Vodafone: 5G at no extra cost on all plans; 5G Ultra (standalone) on Red, Plus and Premier plans. Vodafone SIMs now also use Three’s masts where the signal is stronger, following the VodafoneThree merger.
- Three: 5G at no extra cost, with automatic access to Vodafone’s network at MOCN-enabled sites.
- O2: 5G included on Classic Business Plans.
Ofcom’s Connected Nations 2025 report put outdoor 5G coverage from at least one operator at 97% of UK premises and 5G standalone at 83%, but individual networks ranged from 64% to 89%, so check your sites in our best mobile network UK guide before choosing on price alone.
Is unlimited worth it, or is a big capped plan cheaper?
The gap between the top capped tier and unlimited tells you what you are paying for peace of mind:
| Network | Largest capped plan (24m) | Unlimited (24m) | Premium for unlimited |
|---|---|---|---|
| Three Business | 500GB at £18 (was £23) | £19.17 (offer) | £1.17 a month |
| O2 Business | 25GB at £16 | £17.50 | £1.50 a month |
| EE Business Essential | 100GB at £19 | £25 | £6 a month |
| Vodafone Business | 200GB at £24.17 | £29.17 list | £5 a month at list |
On Three and O2 the premium is trivial, so unlimited is the default for anyone using more than a few gigabytes. On EE and Vodafone, unlimited costs £5–£6 a month more than 100–200GB, which is only worth paying on lines that actually exceed those figures — typically field engineers tethering laptops, video-heavy roles and anyone whose phone is their primary internet connection. Check three months of bills before deciding; on most accounts fewer than one line in five needs unlimited.
Annual price rises on unlimited business SIMs
Because business contracts sit outside Ofcom’s 2025 ban on inflation-linked increases, every quote should show the rise in pounds. On the plans above: O2 adds £1.50 each 1 April; Three adds £0.75 to plans priced £10–£20 and £1.50 to plans over £20.01; Vodafone adds £2.09 on sole-trader plans and £3.01 on limited-company plans each 1 April; EE adds a fixed amount stated in your contract summary each 31 March, with out-of-bundle charges up 5%. Over a 24-month term that is one or two increases; over 36 months, three. Our spend cap guide covers the other bill controls.
How to buy the right unlimited SIMs for your team
- Band your lines by usage from the last three bills. Put only the genuinely heavy users on unlimited.
- Decide roaming per line. Travellers go on Three’s Go Roam plan, EE All Rounder with Roam Abroad, or Vodafone Plus; UK-only staff don’t need to pay for it.
- Separate router use. Anything living in a 4G/5G router gets a data-only SIM, not a phone plan.
- Check coverage per site, then compare dated quotes with VAT, term and the April increase spelled out. We quote EE, Vodafone, O2 and Three side by side and handle porting and eSIM set-up. Request a quote or call 0333 015 2615.
Frequently asked questions
On published 24-month small-business prices checked on 22 September 2026, O2’s Classic Business unlimited SIM at £17.50 a month ex VAT is the cheapest list price, followed by Three’s £19.17 offer (which includes roaming in 49 European destinations), EE at £25 and Vodafone at £29.17 list with a £19.17 promotion running. Vodafone’s Multibuy prices additional unlimited SIMs at £11.67 for five to nine SIMs.
In the UK, on a phone, yes: none of the four networks caps monthly data on its business unlimited plans. The conditions are on speed (Vodafone’s standard plan is capped at 100Mbps), on extreme use (EE may deprioritise or move users above 600GB a month) and on roaming, where fair-use allowances of 12GB (Three), 25GB (Vodafone, O2) or 60GB (EE) apply each month.
Phone plans are sold for use in a handset. EE’s unlimited plans are for the user’s sole use with a 600GB monthly threshold for excessive use, and Three monitors for commercial-scale use that looks like fixed broadband. For a router, buy a data-only plan: EE’s Business Mobile Broadband unlimited plan is £34 a month rolling or £30–£38 on 12 months, and Three, Vodafone and O2 sell data-only SIMs on quote.
EE includes tethering on all single-user business plans and Three includes Personal Hotspot on every business plan, both drawing on the unlimited allowance. Vodafone and O2 don’t publish tethering restrictions on their small-business unlimited plans, but confirm it on your quote. Daily laptop use is better served by a data-only SIM.
Yes on all four networks at no extra cost. EE’s new plans include 5G+ (standalone 5G) from 13 May 2026, Vodafone’s Red, Plus and Premier plans include 5G Ultra, and Three and O2 include 5G on their business plans. You need a 5G handset and, for standalone 5G, possibly a new SIM or eSIM.
Not usually, but the gap varies. On Three the 500GB plan is £18 and unlimited £19.17, and on O2 25GB is £16 against £17.50 unlimited, so unlimited is an easy upgrade. On EE the step from 100GB (£19) to unlimited (£25) is £6, and on Vodafone from 200GB (£24.17) to unlimited (£29.17) is £5 at list, so reserve unlimited for lines that genuinely exceed those allowances.
Reviewed and updated 22 September 2026. Prices, speed caps, fair-use policies, tethering terms and annual increases were checked against the EE Price Guide for Small Business v20.9 (22 July 2026), Vodafone Business SIM-only pages, the O2 Business Shop and Three Business SIM-only pages on the same day. Coverage figures are from Ofcom’s Connected Nations 2025 report (19 November 2025).
Primary sources:EE Price Guide for Small Business (PDF) · Vodafone Business SIM only · O2 Business Shop · Three Business SIM only.
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