Asda Mobile is a mobile virtual network operator, which means that instead of running its own network, it ‘piggybacks’ off another networks.

So far, it’s used EE’s signal, but it’s switching to Vodafone in September.

Asda Mobile customers will need to order a new SIM and put it in their phone before 15 September in order for their phone to carry on working after this date. If you fail to do so you’ll lose your number and any remaining credit or active bundles. You can make your move at any point before this date.

If your phone is locked to the EE network, Asda Mobile can provide you with an unlock code.

As part of the move process, Asda Mobile will ask you for your phone number and IMEI number. If your phone is locked to EE, a four-digit code will be provided which you need to use when your phone asks for an unlock code after swapping your SIM.

Asda says the move will enable customers to access new additions to the mobile network, including unlimited data SIMs, an online account where you can buy bundles, and top-up on the go.

The move to Vodafone will also give Asda Mobile customers access to Vodafone’s 5G network.

How to order a replacement SIM

* Log in to your Asda Mobile account and order it online.

* Call Asda Mobile’s customer services team on 0808 006 2732 for free from your mobile and ask for a new SIM.

* Buy an ASDA SIM for 50p in an Asda supermarket. Once the new SIM is up and running you’ll automatically get the 50p back as Asda Mobile credit.