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Help & Support


What do to with your SIM

Understanding SIM Cards for New SIM only customers / Replacement SIMs / Pay as you go SIMS

We’ll send you a tri-SIM which contains all three SIM sizes available.

Check your new phone carefully to see which size you need to pop out. You can also check the phone instructions or look at your phone’s device guides for step-by-step instructions.

You’ll need to pop out the right sized SIM for your phone from the plastic card. On the back of your card you’ll see your mobile number and SIM serial number.

If you pop out the wrong sized SIM then you’ll need to contact us to get a replacement or order one online and then do a SIM swap to transfer your number across from your original SIM to your new SIM.

If you’re an existing pay monthly customer you can also order a replacement SIM online. Once your new SIM arrives, you’ll need to do a SIM swap from your original SIM to transfer your mobile number across to your new SIM. Please note that when you order a replacement SIM online, we’ll send you a new pay as you go SIM. Once you’ve done your SIM swap, the SIM will activate to pay monthly if you’re a pay monthly customer. If you don’t have your original SIM then please contact us.

You can also chat to us about ordering a new replacement SIM.

If you’re a business customer, please call us on 0345 601 2448

Your SIM will usually need to be inserted into the removable SIM tray or under the battery. If you need help with this, our device guides give you step-by-step instructions.

New phone

Your SIM will already be in your phone so you don’t need to do anything. If you have an iPhone, your SIM will be on the side of the box, so you’ll need to insert it into your new phone.

Upgrading your phone

Your upgrade phone will come with a new SIM card, but you only need to use this if your current SIM doesn’t fit into your new phone.

If you need to use your new SIM, here’s everything you need to switch your number to your new SIM. Whilst your number is switching over, this SIM may show as a Tesco Mobile pay as you go SIM card. This is normal and will change when your number has transferred.

Problems with your SIM?

If you need further help, our social media team are also here to help. You can get in touch with them on Facebook and Twitter.