Frequently asked questions

My postcode or property address doesn’t appear on the checker, why?

Ofcom uses data from Ordnance Survey to provide the dataset used to show mobile coverage for properties in the UK. This data is updated in our checker three times a year, so some properties may not be identified until these updates have been made.

Do you have an API to access the data contained within the checker?

We provide an API based on our mobile coverage data. This is the same data that powers this checker. Details and guidance on the API can be found on our developer portal.

How is the coverage information created and how do you make sure it is accurate?

Data Collection:

The mobile coverage map is based on coverage predictions from the mobile network operators. These predictions are generated using computer programs that simulate the way mobile signals travel from mobile masts and are blocked by any obstructions such as hills, trees, and buildings.

These coverage predictions are processed into a 50 meter by 50 meter grid matrix that covers the entire UK land mass. This data is then uploaded into the Ofcom Coverage Map.

Data Analysis and Verification:

To verify the data, Ofcom perform several tests in the real-world using dedicated measurement hardware across a sample set of different locations in the UK. These tests have shown that the predictions from computer models are generally reliable but cannot guarantee coverage is present in a certain area due to very local factors.

How often is the coverage information updated?

We periodically update the checker with the latest available coverage predictions from the mobile network operators. We aim to update the checker with coverage information every three months, or in line with Connected Nations publications.

The map says that I should have good coverage but I’m not getting a reliable service. Why?

The predictions on the checker are based on the average signal strength across an area, calculated based on how signal is transmitted from an antenna. In some cases there will be a degree of variability between the information presented and real-life experience since our data comes from MNOs predictions.

For example, on average there may be good coverage in a full grid section, but coverage in different parts of that section might vary significantly depending on very local factors, such as trees, buildings and seasonal foliage that cannot be accounted for in these calculations.

Your map is different to the operators’ maps. Why?

The Ofcom coverage map uses mobile network operators’ coverage predictions indicating signal levels at every location in the UK. Because Ofcom's map brings all their predictions together in one place and holds it to a single, independent standard, our map may display different levels of availability of coverage than those seen on the operators' websites. Links to the operators' maps can be found here:

• O2
• EE
• Three
• Vodafone

I live in an area without 4G or 5G coverage, where can I get information about my signal?

2G and 3G networks are gradually being switched off to support the roll-out of the 4G and 5G networks across the UK, so have not been included in this checker.

If required, information on 2G and 3G networks can be found in our Connected Nations reports, in our advice for mobile customers, and directly from the Mobile Network Operators.

What can I do to improve my connection indoors?

If you are experiencing problems with indoor coverage, you may wish to consider some of the solutions that the mobile operators can offer. For example, all the main network operators now allow calls and texts to be made and received over Wi-Fi. You should contact your provider for more information.

Repeaters can also be used to improve your indoor coverage. These devices use outdoor signal to improve indoor coverage. This is done by positioning the device in an area with good outdoor signal so it can retransmit that signal indoors. Further guidance on repeaters can be found here:

Using a repeater to improve your indoor mobile phone signal - Ofcom

Why does the checker say “N/A” or “-1” on the postal district section?

We only show postal district coverage scores when we have prediction data from the MNOs to calculate coverage over the searched district. N/A or -1 is displayed on the checker when this data is not available.

Why do I see unexpected or conflicting scores between coverage and performance across my district?

Unexpected or conflicting scores could be caused by a number of reasons not limited to:

• Coverage and performance use different reporting methodologies tailored to each output which could cause reporting differences when reviewed together.
• Coverage is based on MNO predictions whereas performance is based on crowdsourced measurements. Both have implications that could cause reporting differences.
• The quality of your MNO’s network in your district, such as spectrum (frequency) deployment and overall site capacity introducing additional variables.
• Network congestion including increased user demand during peak times (such as within commuting hours) impacting the network differently at different times.

Further information on how coverage and performance reporting works can be found in their respective FAQ pages.

How does Ofcom measure mobile network performance?

We use crowdsource measurements collected from real mobile users to measure the mobile network performance and the consumer experience of using different mobile services. Measurements are handled by a third-party provider and licenced to Ofcom.

Measurements from smartphones are collected every day, under conditions of normal use. These include measurements in both indoor and outdoor locations to best reflect typical user habits.

The measurements are grouped into postal districts and displayed as a percentage score of samples in the district that passed our user experience acceptance criteria.

While crowdsourced measurements can offer a good representation of real world user experience, performance scores should be considered as a guide since there can be local variations.  

How often is the performance information updated?

Performance percentages are calculated using data over the last 12 months from our last upload date. to upload new performance data every quarter.

Why do I see a performance score when I have no coverage?

Since performance scores are measured across a postal district, there may be times where a spot location does not have coverage, but the district on average has reasonable performance. When this happens, you should follow the coverage score to set your network experience expectation.

Why does the checker say “N/A” on the performance section?

We only show performance scores for each postcode district when all four MNOs have enough performance measurements within the district to pass our statistical confidence threshold (enough measurements to eliminate rogue measurements etc). N/A is displayed on the checker when this threshold has not been met.

What factors can impact performance?

Multiple factors can impact the network performance you experience. Some common factors include:

• Mobile Site: The power of your local mast, and how close you are to it.
• Mobile Device: The availability of local airwaves, the quality of antenna in your phone and if you have a 5G capable device and plan.
• Local Clutter: Hills, buildings, and trees, between you and the mobile mast.
• Network Loading: The capacity of the local mast and congestion in the network, particularly at peak times.
• Environment: Which materials were used to make the building or vehicle you are in.
• Weather/ Season: Bad weather.

Why is performance only available at postal district level when coverage is available at my address? 

Performance and coverage scores are displayed using different geographic methods since they use different methodologies to suit their unique reporting characteristics.

Coverage scores are calculated using MNO predictions that are generated to a high enough resolution to let us estimate coverage at address level.

For performance, we only show scores across a zone when we have enough measurements to pass our statistical confidence threshold (enough measurements to eliminate rogue measurements etc). Our crowdsourced data tends to reach this threshold across postal district sized zones, making this the smallest zone size we can report on.  

Can areas larger than postal districts be used?

If we do not have enough performance measurements within a district to pass our statistical confidence threshold, we will use measurements from the district’s parent postal area. If this happens, all rules, methods, conditions and disclaimers associated with district reporting apply to postal area.  

How should I raise a complaint about my coverage?

You should contact your mobile operator if you are having coverage issues as they may have solutions for your problem. You will be able to find contact details and their complaints procedure on their website.

If your problem is still unresolved after eight weeks, you can complain to an independent Alternative Dispute Resolution (ADR) scheme. You may be able to access ADR earlier than eight weeks if your provider issues a 'deadlock' letter. Your provider will tell you which scheme it is a member of, or you can use our ADR checker.

Ofcom is unable to get involved in individual disputes, but we do log and monitor the complaints we receive through our monitoring form Complain about mobile, phone or internet services - Ofcom to help inform our work.