The UK's 'best mobile phone network' has been revealed but it is not O2, EE, Vodafone or Three

The 'big four' mobile phone networks are 'letting down' users in terms of value for money and customer service, according to a new study. Consumer champion Which? has revealed that O2, EE, Vodafone and Three each ranked lower than lesser-known rivals.

Those four providers currently service three quarters (76pc) of customers in the UK, according to Ofcom, but Which? say the flexibility of virtual networks keeps mobile costs down and could better support consumers facing a household budget squeeze. Their customers pay on average almost £10 a month less than big four customers across all contract types.

Three scored the lowest of the big four and received the lowest rating of any network for reliability. Nearly half (45pc) of Three users experienced problems in the past year compared to three in ten (29pc) across all mobile network customers surveyed.

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Despite this, it was actually a network that uses the same infrastructure as Three that came out on top, WalesOnline reports. Smarty - a virtual network that offers a monthly rolling SIM-only service - was ranked as the best mobile phone provider. Giffgaff, Plusnet and Tesco were joint second, while the likes of Voxi, Sky, iD Mobile, and Lebara all finished above the big four.

The largest UK network, EE, came 11th out of the 16 providers analysed with users reporting mediocre customer service, technical support and value for money. The network’s download speeds were the only category to gain it a four-star rating.

Natalie Hitchins at Which? said: “The vast majority of mobile users are with one of the big four providers, but our research suggests consumers could