What is a business mobile line?
A business mobile line is a mobile number and plan used for work. It can be a SIM only plan, a handset contract or an extra line added to an account you already have.
Plenty of small firms get their first business mobile line by accident. A sole trader starts using a personal phone for work, and one day the customer calls, the family calls and the supplier calls all land in the same pocket. A separate business mobile line is how most people pull those apart.
The rules that protect you depend on how big your business is. Everything below comes from Ofcom’s page on the General Conditions that protect business customers, which we read on 5 November 2026. That page was first published on 25 January 2016 and last updated on 17 January 2025, so check it for anything newer before you rely on it.
What rules cover a new business mobile line?
Ofcom splits the protections into three groups: all businesses, small and medium firms with fewer than 250 employees, and firms with ten employees or fewer. A new business mobile line comes under the first group whatever your size.
For all businesses, Ofcom says providers must offer at least one 12 month contract for each service. They must also give at least one month’s notice of a change to the contract that is not to your benefit, with the option to leave without a penalty.
Providers must also send end of contract notifications and annual best tariff notifications. These are the reminders that stop a business mobile line sliding onto a worse deal without you noticing.
Contracts have to include minimum information, such as the minimum service quality levels and the prices and tariffs, and providers must publish service descriptions, tariffs and standard contract conditions. Bills have to be accurate and the billing information adequate and up to date.
What extra protections do firms with ten employees or fewer get?
Firms with ten employees or fewer get more, according to Ofcom. If that is you, a provider has to follow these rules when you take a business mobile line.
- Information in writing: key contract details such as charges, contract length and how to cancel must be given before you are bound, plus a one page contract summary, or three pages for a bundle.
- A 24 month limit: phone and broadband contracts cannot be offered with a commitment period longer than 24 months, and this also applies to bundles.
- Consent to renew: your contract cannot be renewed at the end of the commitment period without your consent.
- No quiet extensions: buying extra services or equipment cannot extend your existing contract unless you agree.
- Exit terms: termination terms must not discourage you from switching, including on bundles.
The size of your business decides which group you fall into, so if you are close to the ten employee line it is worth knowing which rules your provider is applying to your contract.
Key takeaways
- Every business can ask for at least one 12 month contract on a business mobile line.
- Firms with ten employees or fewer cannot be offered a phone contract longer than 24 months.
- You are entitled to key contract details in writing before you sign.
- Check the contract length before you add a handset to an existing business mobile line.
Can you keep your number when you move a business mobile line?
Yes. Ofcom’s switching rules protect mobile customers whether or not they keep their number, and keeping it is the normal route when you move a business mobile line to another provider.
The practical step is the same as on a personal line: ask your current provider for a PAC code, then give it to the new provider when you order. Ofcom’s business page does not set out the porting timescales, so we have not quoted any here. Our PAC codes guide covers how the code works and what to expect, and our guide to switching business mobile covers the rest of the move.
One thing worth doing before you ask for a code: check what notice your current contract requires and whether you are still inside a commitment period, because an early exit can carry a charge.
What helps keep a business mobile line bill under control?
For firms with ten employees or fewer, Ofcom says providers must tell you when a service in your plan is fully used up. That notice must also say what charges apply outside the plan.
That is the rule that stops a sales phone quietly running past its data allowance all month. If your firm is above the ten employee line, the notice is not guaranteed, so ask your provider what alerts it offers and whether you can set a spend cap.
Ofcom also says providers must have complaint handling procedures that meet the minimum standards in its approved complaints code. They must also belong to an Ofcom approved alternative dispute resolution scheme and tell you how to use it.
What should you check before adding a business mobile line?
A business mobile line is easy to add and easy to forget. A few checks before you sign are worth the five minutes.
Work out how long you are happy to be tied in. A SIM only line can be much more flexible than a handset contract. Our guide to business mobile contracts explains the difference between fixed, flexible and rolling terms.
Check coverage where you actually work. A business mobile line that drops out at the unit or the client’s office is a poor line, whatever the price. Our business mobile network guide explains how to test sites.
If anyone travels for work, ask about roaming before you sign rather than after the first bill, since roaming terms sit outside the plan allowance.
Prices change often, so we have not listed any here. A comparison shows what is on offer today, and Switcheroo can show business mobile deals side by side.
Frequently asked questions about a business mobile line
- Can I get a business mobile line as a sole trader?
- Yes. Ofcom’s protections apply to business customers, and the extra rules apply to businesses with ten employees or fewer. A sole trader falls in that group.
- How long can a business mobile line contract be?
- Ofcom says phone and broadband contracts cannot be offered with a commitment period longer than 24 months to firms with ten employees or fewer. Providers must also offer at least one 12 month contract for each service.
- Can I keep my number on a new business mobile line?
- Normally yes. Ofcom’s switching rules protect mobile customers whether or not they keep their number, and you ask your current provider for a PAC code to move it.
- What happens if my provider changes my contract?
- Ofcom says you must get at least one month’s notice of a change that is not to your benefit, and the option to leave without a penalty.
Sources
- Ofcom, General Conditions that protect business customers, first published 25 January 2016 and last updated 17 January 2025. Supports the three groups of business customer, the 12 month contract offer, one month’s notice of a change that is not to your benefit with a penalty free exit, end of contract and annual best tariff notifications, contract and published information requirements, accurate billing, and for firms of ten employees or fewer the written information and one page summary, the 24 month commitment limit, consent to renew, no extension without consent, termination terms that do not discourage switching, the allowance used up notification with out of plan charges, the approved complaints code and membership of an Ofcom approved dispute resolution scheme.
Checked 5 November 2026. Ofcom’s business page does not cover number porting timescales, so none are quoted here.
