Three Business Mobile Plans Explained: Tariffs, Tiers and What's Included in 2026
Three Business Mobile Plans Explained: Tariffs, Tiers and What's Included in 2026
Last updated: April 2026
If you have ever tried to compare Three Business plans by reading the Three website, you know it is harder than it should be. There is a "Simple Business Plans" page that gives you four boxes (voice or data, contract length, data tier, what is included), and the page is genuinely simple, but it does not actually answer the question of which plan you should buy. The marketing makes everything sound included. The pricing depends on factors that are not on the page. The "5G ready" line appears on every plan whether you have a 5G phone or not.
This guide cuts through that. It explains what the actual decisions are, what each option means in practice, and how to pick the right plan for each user in your business. We do this analysis on every quote at Compare The Networks, so the framework here is the one we use with real clients.
The Four Decisions You Need to Make
Every Three Business plan is built from four choices:
- Voice and text plus data, or data only?
- How much data does this user actually need?
- How long do you need the contract for?
- What extras do you want included?
That is the whole product. Once you have answered these four, you have picked your plan. The trick is answering them honestly based on actual usage, not based on what the user thinks they need or what someone in marketing said sounded reasonable.
Decision 1: Voice + Text + Data, or Data Only?
Most Three Business plans include unlimited UK voice and text along with the data allowance. This is the standard product and is right for the majority of business users. People who use a phone as a phone want voice, text, and data on the same SIM.
Data-only plans are a different product. They are designed for SIMs that go in non-phone devices: 4G or 5G routers, IoT sensors, mobile broadband for tablets, fleet tracking units, vending machine connectivity, and so on. Data-only plans do not have voice or text allowances at all, but they are typically cheaper per gigabyte than voice plans.
If you are buying a SIM for an actual phone, you want a voice + text + data plan. If you are buying a SIM for any kind of equipment that does not need to make calls or send texts, you want a data-only plan. The cost difference is meaningful at scale, especially if you have multiple IoT or router SIMs in the business.
Decision 2: How Much Data?
Three Business data tiers range from 3 GB at the bottom up to genuinely unlimited at the top. The exact tiers vary by plan family, but the typical structure is:
- 3 GB: Light users. Office staff who are on wi-fi at work and at home, who only really use mobile data when commuting or out of the office. Probably under-uses what they have.
- 25 GB: Moderate users. People who occasionally tether for work, who travel for business sometimes, who rely on mobile data when away from wi-fi. The middle ground.
- 80 GB: Heavy users. Sales reps, field workers, anyone who runs cloud apps from the phone all day. The right tier for most mobile-first knowledge workers.
- 500 GB: Very heavy users. Anyone who tethers a laptop daily, anyone uploading large files from the field, anyone whose phone is doing work that would otherwise need fixed broadband.
- Unlimited: Genuinely uncapped. Best for users who would otherwise risk hitting 500 GB, and for users who you simply do not want to think about.
The honest test is to look at actual usage data over the last 6-12 months and see what each user actually consumes. Most businesses overpay because they bought too much data for one user and not enough for another. Right-sizing on real data is the single biggest source of savings on a contract renewal.
We use the Three Analyst dashboard to do this for clients with existing accounts. For new customers we estimate based on role and use case, then review after a few months.
Decision 3: Contract Length
Three Business plans come in three contract lengths:
24 months. The standard. The cheapest per-month price. The right choice for any line you are confident you will keep for two years. Most business mobiles fall into this category.
12 months. A premium over 24 months but more flexibility. The right choice if you are unsure about your team size, if you are testing a new role, or if you want to align with a renewal cycle on a different contract.
30 days. The most expensive per month, but no commitment. The right choice for genuinely short-term needs: a contractor on a 6-week project, a covering staff member, a temporary office that will close in two months.
You can mix contract lengths across SIMs in the same business account. Your core team can be on 24-month contracts while a few flexible lines are on 30-day. This is a useful pattern for businesses with seasonal or project-based staffing.
Decision 4: What Is Included as Standard
Every Three Business plan in 2026 includes:
- 5G ready. If you have a 5G handset and you are in a 5G coverage area, you connect to 5G at no extra cost. There is no 5G upgrade fee.
- Personal hotspot. Tethering is included. You can share your phone's data with a laptop or other device.
- Free wi-fi on the London Underground. Three is part of the network providing wi-fi on the Tube. If you commute through London, your phone connects to it automatically.
- Spend caps. Optional. Set a limit per line so out-of-bundle charges cannot exceed it. Useful for control.
These are not extras to negotiate. They are part of the standard plan. If a Three sales rep tries to charge you for any of these, push back.
What is NOT included by default:
- EU roaming. Add Inclusive Roaming Europe for free EU travel, or pay £2/day on the standard tariff.
- Worldwide roaming. Add Inclusive Roaming Around the World or Around the World Extra.
- Data Passport (unlimited data abroad). £6/day add-on, used on demand.
- Static IP. Optional for data-only plans.
- Insurance. Optional, third-party.
Mixing Plans Across Your Business
This is where Three is genuinely better than the other UK networks. Three Business plans are SIM-by-SIM. You can run a 20-line account where every SIM is on a different plan. There is no penalty for the mix.
The smart play is almost always to mix:
- Some lines on Unlimited (the field workers and heavy travellers)
- Some lines on 80 GB (the moderate users)
- Some lines on 25 GB (the office hybrid workers)
- Some lines on 3 GB (the office staff who barely use mobile data)
- Some data-only SIMs in routers or IoT devices
Each user gets the right tariff for their actual usage. The total monthly cost is significantly lower than blanket-applying a single plan to the whole fleet. We have seen accounts cut their bill by 25-40% just by right-sizing the plan mix at renewal.
How Three Plans Compare to the Other Networks
O2 has fewer tiers and is less flexible per SIM. EU roaming is included on every line, which is convenient if you want it and slightly inefficient if you do not.
Vodafone has comparable tiers but is priced higher on list. Negotiation is possible on big contracts. Plan flexibility is similar but the structure is less explicit.
EE has comparable tiers but is the most expensive of the four for most use cases. Best 5G coverage, weakest on roaming.
Three wins on price for most small and mid-sized businesses, has the most explicit per-SIM flexibility, and offers the best worldwide roaming product. Coverage is now genuinely competitive post-merger.
For a typical UK SME of 5-50 lines, Three is usually the cheapest option that meets the requirements. For larger businesses, the answer depends on what else you are negotiating in.
Example: A 15-Line Business
To make this concrete, here is a real-world example of what a 15-line Three Business contract might look like.
Business profile: A regional sales team of 15 people. Three senior managers who travel internationally. Eight field reps who travel within the UK and occasionally to Europe. Four office staff who never travel.
Plan mix:
| Role | Lines | Plan | Roaming |
|---|---|---|---|
| Senior manager | 3 | Unlimited 24mo | Inclusive Around the World Extra |
| Field rep | 8 | 80 GB 24mo | Inclusive Europe |
| Office staff | 4 | 25 GB 24mo | None (passes when needed) |
That is 15 lines, three different plan tiers, two different roaming structures, all on a single Three Business account.
Cost compared to alternatives:
- Three with the right mix (above): Lowest total monthly cost
- Three with everyone on Unlimited Around the World Extra: ~25-35% more per month for benefits the office staff never use
- O2 equivalent: ~10-15% more on list price (Three discounts more aggressively at this size)
- EE equivalent: ~15-20% more on list price
The exact numbers vary by current pricing. We update them on every quote.
How to Get the Right Mix Without Doing the Maths Yourself
Honestly, the way to do this is to have someone who does it every day look at your account. We do that for every customer at Compare The Networks as part of a free quote.
What we do:
- Look at your actual usage data for the last 6-12 months (or estimate from role if it is a new account)
- Map each user to the smallest plan that comfortably covers their real usage
- Add the right roaming product for each user based on travel pattern
- Compare the resulting Three quote against equivalent quotes on O2, Vodafone, and EE
- Tell you which network and which plan mix is genuinely cheapest
This takes us about an hour for a typical small business and saves clients real money over 24 months. Free quote here.
Frequently Asked Questions
Q: Can I change the data tier on a SIM mid-contract?
Plan upgrades (more data) are usually allowed mid-contract and we handle them on behalf of clients. Plan downgrades are sometimes restricted to renewal time.
Q: Is 5G included in every Three Business plan?
Yes. There is no 5G upgrade fee. If your phone supports 5G and you are in a 5G coverage area, you connect to 5G automatically.
Q: Does the plan include voicemail and call forwarding?
Yes. These are standard features on all Three Business plans.
Q: Can I move my number from another network onto a Three Business plan?
Yes. Number porting is free and takes typically 1-2 working days. We handle the porting process for clients as part of the switch.
Q: How do annual price increases work on Three?
From January 2025, OFCOM banned CPI/RPI-linked price rises. Three (along with the other major networks) now applies a fixed £2.50 + VAT per month increase each April. This is shown in pounds and pence so you know exactly what you will pay.
Q: What is the cheapest Three Business plan?
Pricing changes regularly and depends on line count, contract length, and data tier. The 3 GB 24-month plan is typically the cheapest entry point. Get a quote for current numbers.
Q: Can I get a Three Business contract for just one line?
Yes. Three sells single-line business plans, although the per-line price is usually higher than multi-line. If you have 3+ lines, the price drops significantly.
Q: Is there a Three Business plan with no contract?
The 30-day plan is rolling, not contracted. You can cancel any time with one month's notice. It is more expensive per month than the 24-month equivalent but offers maximum flexibility.
Q: How does Three Business Dynamic differ from Simple Business Plans?
Three Business Dynamic is a separate product line for accounts with 25-250 SIMs. It has its own pricing, its own roaming structure (Go Roam in Europe is included by default), and is sold via direct account management rather than off-the-shelf. Talk to us if you are at that scale.
Q: Does the plan include a handset?
You can add a handset to any Three Business plan as a separate component. SIM-only plans are cheaper but you need to bring your own phone. Handset bundles roll the device cost into the monthly fee.