Smartphones are a window to all the apps and services we rely on every day, but when you’re not on the home Wi-Fi, you need as much mobile data as possible. This can be expensive depending on your mobile network provider, but one UK telco is stepping up and offering you a free SIM with unlimited data, calls and texts - as long as you’re attending one of several music festivals this summer.

Three UK is offering anyone attending the Parklife, Wireless, TRNSMT, Latitude, Reading & Leeds or Wilderness festivals to register for a free eSIM trial, with the completely unlimited data, calls and texts lasting for seven days once you start using it.

This means if you are going to one of these festivals and are worried you might run out of data (or simply want to give the Three network a go), you will be able to sign up for a free eSIM and use it while you dance the night away to your favourite acts.

A Three spokesperson told Express.co.uk that festival attendees will receive a link to sign up before their festival begins, so keep an eye on your email inbox and text messages.

“When on site at the festivals, eSIM customers can party like a Three customer too and get exclusive access to the Three platform for the best viewing experience at the festivals and discover all the onsite offers including free phone charging,” Three said.

“All they need to try the network for free is an eSIM-compatible smartphone – no need to change their number.”

Unfortunately, you can't take part if you're already a Three customer.

That’s the small print here. Not all smartphones have eSIM capabilities, so you’ll have to check. If you have an iPhone, you are probably in luck, as every iPhone since the XS and XR in 2018 have had eSIM tech built in.

Many Android phones from Samsung, OnePlus, Google and others also have eSIM, but a quick Google search of your phone model and if it has eSIM should let you know. You can also head into the settings app and have a look.

eSIM works just like regular SIM cards, except it’s all virtual and there’s no need for a physical card. Instead, the mobile plan is assigned to your phone. As Three says, you can run this eSIM plan in tandem with your regular number. I use an eSIM when travelling, and I change the settings in my phone so the data comes through the eSIM but calls and texts still go to my regular number.

“We power some of the UK’s most iconic festivals with our 5G Network and we know how important it is to stay in touch with your friends and loved ones this summer,” said Andrew Foy, Director of New Products and Propositions, Three UK.

“Helping keep music fans connected with this trial will also give people the chance to experience first-hand the glow of being a Three customer and our network.”

The calls, texts and data will work in the UK only, so you can’t jump on a plane to Europe and still expect it to work. It’ll last for seven days from when you activate the eSIM.