Smaller mobile providers are outperforming bigger networks in terms of reliability, price and customer service, according to the latest annual survey from consumer group Which?.

While EE, O2, Vodafone and Three dominate the mobile industry in the UK, there are signs that smaller networks that ‘piggyback’ on their services are going above and beyond in key areas that matter to customers.

giffgaff, which uses O2’s network, is deemed to be better value for money, while Utility Warehouse and Smartly, two lesser-known services, managed to beat EE and Three, respectively.

The survey found that Three was the worst of the ‘big four’ providers, with network reliability being a sore spot for customers and a third admitting that they had left the service due to poor coverage.

Vodafone did better in this area as around 25% of customers rated the company’s reliability as excellent, but it still fell short of expectations on value and customer service.

EE finished in the bottom half of the rankings of the 15 providers, but there was better news for O2, which came joint fifth due its “ease of contact”.

Which? director of policy and advocacy Rocio Concha said that bigger providers had been “outshone” in the latest survey and that networks should all aim to be reliable, affordable and ready to support customers when needed.

Concha concluded: “If customers are out of contract but happy with the service they’re receiving, they should try negotiating a new deal, but if all else fails it might be time to switch.”