Are you wondering why your new or replaced Tesco SIM wont activate? Have you tried restarting your phone but facing the same issue? This article will show you how to set up your cellphone and activate your new or replacement Tesco SIM.

Tesco Mobile, a virtual mobile network provider, is based on O2’s infrastructure and covers 99% of the UK population. You can get a Tesco Pay Monthly or Pay As You Go SIM with and without a cellphone.

Tesco’s mobile service is top-notch. However, quite a few users complain that their Tesco SIM won’t swap or activate after 24 hours. Most of the time, new users who get the Pay Monthly SIM for the first time or opt for a replacement SIM face the activation issue. Let’s find out what steps you can take to fix the problem when your Tesco sim wont activate

Why do I need to swap my Tesco SIM card?

Why do I need to swap my Tesco SIM card?

When you purchase a SIM from Tesco, they send you a Tri-SIM to accommodate the standard, micro, and mini size. This way, you can break the SIM according to your device and use it straight away. But, after some time, when you upgrade your cellphone, it may not work with your existing Tesco SIM size.

Furthermore, you may have lost your phone, or your existing SIM got damaged. In all of these cases, you need to get a new SIM from Tesco.

If you have upgraded to a new phone and it takes the same size SIM, you can put the old SIM into your new phone and use it right away. However, if the size doesn’t match, you need to get the replacement SIM from Tesco and swap it with the old SIM to keep the things working in a usual way.

What do I need before swapping my Tesco SIM?

Before you swap your number to the new Tesco SIM, make sure to transfer any stored data such as contacts from your old SIM to the new device. That is if you have your Tesco SIM with you. Afterward, when you activate the new SIM, you can copy all the contacts from your device to your new SIM.
We recommend that you store your contact on a cloud from the start to avoid any inconvenience due to an unfortunate event resulting in SIM damage or losing your phone.

How do I swap my Tesco SIM?

How do I swap my Tesco SIM?

If you have got a new SIM from Tesco for any reason, do the following steps to initiate the swap process.

  • Insert the old Tesco SIM on your phone and open the Message app.
  • Next, start a new conversation and type SWAP in the text field.
  • Now send the text to 23424 and wait for the Tesco instructions.
  • In a few moments, you’ll receive a reply from Tesco, and they will ask you for the new SSN (SIM serial number).
  • Look at the side of the new SIM card and locate the SSN. If you have a standard or micro SIM, SSN is 19 digits, while nano-SIM SSN is 13 digits long.
  • Send your SIM SSN in reply to the Tesco message (Tesco will ask you to re-enter SSN if you send the incorrect digits).
  • Wait for the confirmation message that Tesco has accepted the new SIM details.
  • Finally, Tesco will swap your number on the new SIM.

If there is something wrong with the Tesco SIM swap process, it won’t activate later. You can contact Tesco customer support to troubleshoot the issue.

How long will my Tesco SIM swap take?

When you swap or transfer your number to your new SIM, your Pay Monthly SIM may show as Pay As You Go SIM. However, this is temporary and will change back when your number is swapped to the new SIM.

The SIM swap takes up to 24 hours. You’ll get the confirmation when your old Tesco SIM loses signals. At this time, put in the new SIM on your phone and restart it to complete the swap process.

How do I activate my Tesco SIM?

How do I activate my Tesco SIM?

To activate your new Pay Monthly Tesco SIM on your existing or upgraded device, you only need to make a call. However, Pay As You Go Tesco users can top up their balance and then make their first call for the changes to take effect.

Same like the Tesco SIM swap process, Tesco’s Pay Monthly customers will be seeing a Pay As You Go SIM sign for 24 hours on their device until the SIM is fully activated.

If you are a Tesco SIM 0nly customer, make sure that your phone works with the Tesco SIM. You may need to ask your old mobile network provider to unlock the phone for you. When this is all done, you can start the SIM swap and activation process. 

Additionally, if you have an iPhone and want to use the Tesco SIM with it, go to the phone settings and update your number under Phone –> My Number. Afterward, make a call to activate the Tesco SIM.


We hope that this guide helped you find the cause of when your Tesco SIM won’t activate.

Make sure to set up the device and swap the SIM and then move to SIM activation. You may experience activation issues if Tesco service is down in your area or you are experiencing Tesco coverage issues.