Best mobile network 2021: The top UK networks for speed, value and customer satisfaction

Choosing between the UK’s mobile networks never gets any easier. Whether you’re looking for a new phone or a monthly SIM-only deal, there are dozens of operators, plans and bundles to pick from, and it’s all too easy to sign up to what looks like a great deal, only to find you could have had a lower price or more monthly data elsewhere. 

Not only do you have the four major 4G and 5G mobile networks to choose from but also dozens of virtual operators, each offering their own SIM-only bundles or smartphone plans, and performance, price and customer service can vary massively. Bagging the best deal takes work.

Luckily, we’re here to do that work for you, combing through the different networks and their plans and packages to find the best options for every type of user. We’ve compared prices, features and add-on services, and factored in the latest performance and coverage figures from RootMetrics, whose researchers painstakingly roam the length and breadth of the UK testing signal strength, connection speeds, reliability and more.

What’s more, we’ve brought in the results of our Mobile Network Awards 2021 survey, along with the latest customer service report from Ofcom and the Net Promoter Scores from this year’s UK Regulators Network scorecards. These cover how likely users of a network are to recommend it to a friend. You’ll find this information summarised in the tables below each review.

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The best mobile networks in 2021

1. Sky Mobile: The best mobile network for happy customers

Price: From £6 to £30 a month, SIM-only | Find out more at Sky Mobile

Sky Mobile is the runaway winner of the Expert Reviews Mobile Network Awards 2021, scoring wins in all four categories, including customer service, value and reliability. The Sky Mobile customers we surveyed couldn’t say enough nice things about the network. Some 98% were satisfied or very satisfied with its customer support, 96% felt they were getting good value for money, and 96% would recommend it to a friend. Sky Mobile had some of the best results for performance and reliability in our survey.

You might have to spend some time trying out different contract terms and upfront payments but this network has some of the best deals on new smartphones, too, and an excellent range of flexible SIM-only plans, especially if you’re a fairly casual user wanting 8GB to 20GB of monthly data. These include some exceptional features, particularly a data rollover that allows you to bank your unused data for up to three years.

While its speeds are limited by its reliance on O2 as a host network – it’s still the slowest of the four major networks according to RootMetrics – 4G speeds are improving and you can get a fast 5G connection in a growing number of UK towns and cities. Ofcom hadn’t published its own figures for Sky this year, but we do know that it has some of the lowest figures for customer complaints in the business.

Affordable, reliable and backed by great support, Sky Mobile is a brilliant network – and an even better bet for existing Sky subscribers, with streaming apps that won’t use your data while you’re watching Sky TV on the go.

Read our full Sky Mobile review for more details

Key specs – Network type: Virtual network operator (O2); Minimum plan: £6/mth, 2GB, unlimited minutes and texts; Maximum plan: £30/mth, 60GB data, unlimited minutes and texts; Discount options: None; Data rollover: Yes; Additional features: Spending cap, unlimited streaming of Sky apps 

Industry average

Sky Mobile scores

Satisfaction with service overall



Satisfaction with value for money



Complaints to Ofcom per 100K subscribers



Net Promoter Score



Find out more at Sky Mobile

Price: From £6 to £35 a month, SIM-only | Find out more at Giffgaff

With its flexible approach and great value Goodybags, Giffgaff has always been a great network for value, and it’s also the runner-up in three out of four categories in the 2021 Expert Reviews Mobile Network Awards. While it falls just behind Tesco Mobile on Customer Support, it’s second only to Sky Mobile on reliability and value, with 94% of users either “satisfied” or “very satisfied” with the network when it comes to bang for buck. Meanwhile, Ofcom’s most recent figures put it out in front on value for money, with decent scores for service and support as well.

Giffgaff’s cut-price plans run the gamut from a basic £6/500MB package to an unlimited Golden Goodybag for £35 a month, and there are some excellent deals at all price points in between. What’s more, while all Giffgaff plans work on a flexible, 30-day basis, where you can change or cancel at any point, the network makes it worth your while to set up a recurring Golden Goodybag plan, which boosts the normal £10/8GB plan to 10GB of data and the £15/15GB plan to 25GB. As with Tesco Mobile and Sky Mobile, performance is limited by the use of O2 as a host but O2’s 4G speeds have improved and there’s real potential in its 5G services. If you’d like to save some cash and still get an excellent, reliable service, look no further.

Read our full Giffgaff review for more details

Key specs – Network type: Virtual network operator (O2); Minimum plan: £6/mth, 500MB, unlimited minutes and texts; Maximum plan: £35/mth, unlimited data, minutes and texts; Discount options: None; Data rollover: No; Additional features: Spending cap


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