TL;DR
- “Unlimited” data plans in the UK often include a fair use policy that may throttle speeds or restrict certain activities above a stated threshold.
- Under Ofcom’s General Conditions and retained Open Internet rules, operators must publish their traffic management and fair use policies clearly before and after sale.
- Temporary, non-discriminatory congestion management at peak times is permitted; permanent throttling of specific applications generally is not.
- Operators must provide a summary information document at point of sale disclosing any restrictions that may affect the service.
- If a fair use restriction was not clearly disclosed before you signed up, you may have grounds to complain to the operator and, if unresolved, escalate to an approved Alternative Dispute Resolution scheme.
What fair use means in a mobile data context
A fair use policy (FUP) is a contractual mechanism that operators insert into plans marketed as “unlimited” to manage consumption they regard as atypical or commercially damaging. In practice, a FUP may impose a soft speed cap above a stated monthly data threshold, restrict certain uses such as tethering or video streaming at the highest quality tier, or require the operator’s consent before particular high-volume activities.
The term “fair use” has no statutory definition in UK telecoms law, which means operators have considerable freedom in how they draft the policy. What the law does constrain is the obligation to disclose the policy and the manner in which traffic management measures may be applied. Consumers who do not read their terms and conditions carefully may therefore be surprised to find that their “unlimited” plan does carry practical limits.
The legal framework: Ofcom General Conditions and Open Internet rules
Ofcom’s General Conditions of Entitlement (updated periodically and published on Ofcom’s website) set out the transparency obligations that electronic communications providers must meet. General Condition C1 requires that pre-contract information be provided to consumers in a clear, comprehensive, and easily accessible form. This includes information on any traffic management policies that could affect service quality.
The UK also retained, post-Brexit, the substance of the EU’s Open Internet Regulation (Regulation (EU) 2015/2120) through the European Union (Withdrawal) Act 2018. The retained rules, overseen by Ofcom, prohibit operators from blocking or slowing specific internet services on a discriminatory basis and require end users to have the right to access and distribute information without restriction, subject only to defined exceptions such as legal obligations, network integrity, and temporary congestion management.
Traffic management at peak times: what is permitted
Ofcom permits proportionate and temporary traffic management measures applied to all users equally during periods of genuine network congestion. An operator may, for example, reduce the maximum data rate for all users on a congested cell during peak evening hours without breaching Open Internet rules, provided this is disclosed in their traffic management policy and applied in a non-discriminatory way across comparable categories of traffic.
What operators may not do under the retained Open Internet rules is permanently throttle a specific application category—for example, video streaming services—while leaving other traffic unrestricted, unless this is part of a clearly disclosed specialised service or a permitted exception. They also cannot block a competing service on a discriminatory basis. Ofcom has published guidance on its interpretation of these provisions and can take enforcement action against operators that breach them.
| Requirement | Regulatory basis | When it applies | Operator obligation |
|---|---|---|---|
| Pre-contract disclosure of fair use policy | Ofcom GC C1 | Before customer signs up | Must be clear, comprehensive, easily accessible |
| Summary information document | Ofcom GC C1 | At point of sale | Must include speeds, restrictions, and fair use thresholds |
| Traffic management policy publication | Retained Open Internet Regulation | Ongoing | Must be published and kept up to date on operator website |
| Non-discriminatory application of measures | Retained Open Internet Regulation | Whenever measures are applied | Cannot target specific services or competitors |
| Notification of material contract changes | Ofcom GC C1 & Consumer Rights Act 2015 | Before change takes effect | Minimum 30 days notice; customer may exit without penalty |
What a fair use policy document must disclose
Under Ofcom’s General Conditions, the summary information document provided at point of sale must include the minimum and normally available data speeds, and any conditions that limit data rates or volumes. If a fair use policy imposes a speed throttle above a specific usage threshold, that threshold and the speed to which the connection will be reduced must both be stated. Vague language such as “very heavy users may experience reduced speeds” without quantification is not considered adequate disclosure under Ofcom’s published guidance.
Operators are also required to notify customers in advance if they intend to make a material change to an existing fair use policy mid-contract. Under Ofcom’s rules, a materially detrimental change—such as introducing a new speed cap that did not previously exist—gives the customer the right to exit the contract without paying an early termination charge. The notification period required is at least 30 days, giving consumers time to assess their options.
How to find out whether your unlimited plan has a fair use cap
The most reliable source is the full terms and conditions provided with your contract, or the current version on the operator’s website. Look specifically for sections headed “fair use”, “acceptable use”, or “network management policy”. The summary information document (sometimes called a “key facts indicator”) issued at point of sale should also state any restrictions in plain English.
If you cannot locate the policy or find it unclear, you can contact your operator in writing and ask for a written explanation of any data speed restrictions or usage caps that apply to your plan. If the operator cannot or will not clarify, or if you believe a policy is being applied that was not disclosed at sale, you can raise a formal complaint with the operator. If unresolved after eight weeks, you may escalate to Ofcom’s approved Alternative Dispute Resolution (ADR) schemes—currently Ombudsman Services: Communications or CISAS—whose decisions can be binding on the operator.
What this means in practice
Marcus, a graphic designer in Birmingham, subscribes to an “unlimited” mobile data plan. In his first three weeks he uses around 40 GB with no noticeable issues. In the fourth week, after exceeding what turns out to be a 100 GB fair use threshold buried in his terms, his speeds are throttled to 1 Mbps for the remainder of the billing month. He was not warned in advance during that billing period. Marcus checks his operator’s traffic management policy and confirms the threshold exists, but the summary document he received at sign-up described the plan only as “unlimited data” without mentioning the threshold. He raises a formal complaint on the basis that the restriction was not adequately disclosed before contract, which the operator must acknowledge and investigate within the timescales set by Ofcom.
Related Guides
How we verified this
This article draws on Ofcom’s General Conditions of Entitlement (in particular General Condition C1), the retained Open Internet Regulation (EU) 2015/2120 as incorporated into UK law via the European Union (Withdrawal) Act 2018, Ofcom’s published guidance on traffic management, and the Consumer Rights Act 2015.
Disclaimer: Kaeltripton.com is an independent UK editorial publisher. We are not regulated by Ofcom or the FCA and we do not sell or arrange mobile services, insurance, or financial products. This content is for general information only and is not legal, financial, or technical advice. Rules, prices, and operator policies change. Verify the current position with Ofcom, GOV.UK, the ICO, or your provider before acting. ICO registered ZC135439. Last reviewed: 2026-06-05.
Frequently Asked Questions
Is unlimited mobile data really unlimited?
Not always in practice. Many UK plans marketed as unlimited include fair use policies that throttle speeds above a certain monthly usage threshold, restrict tethering, or apply temporary speed reductions at peak times. Ofcom requires operators to disclose these restrictions clearly before you sign up, so the detail should be in your summary information document or the full terms and conditions.
What is fair use on a mobile data plan?
A fair use policy is a contractual clause that allows the operator to manage or restrict data use that it considers atypically high or commercially unsustainable. It may impose a speed cap above a stated threshold, restrict specific types of use such as tethering, or apply temporary congestion management. The policy must be disclosed before sale under Ofcom’s General Conditions.
Can my mobile operator slow my data for heavy use?
Yes, within limits. Operators may apply proportionate traffic management during genuine network congestion, and may reduce speeds above a fair use threshold if this is clearly stated in the contract. However, permanent throttling of specific applications on a discriminatory basis is not permitted under the UK’s retained Open Internet rules, which Ofcom enforces.
What must a fair use policy disclose?
Under Ofcom’s General Conditions, a fair use policy must state the specific usage threshold at which restrictions apply, the speed to which the connection will be reduced, and the duration of the restriction. Vague references to “heavy use” without quantification are not considered adequate. Operators must also notify customers before materially changing a fair use policy mid-contract.
How do I know if my unlimited plan has a fair use cap?
Check the summary information document you received at point of sale, and the full terms and conditions or network management policy published on your operator’s website. Look for sections headed “fair use”, “acceptable use”, or “network management”. If these are unclear, write to your operator requesting a plain-English explanation of any speed restrictions or data thresholds on your plan.
