How to activate your Sim card

Full help to get your new Sim working

If you've just got your hands on a shiny new Sim card, congratulations. Switching your Sim (the chip that dictates your allowance) can unlock huge savings. Now comes the crucial step of activating it so you can start enjoying all the benefits and stay connected.

Looking for a cheap Sim deal? See our top Sim deals or use our Cheap Mobile Finder tool comparison for 1,000s of deals from more than 50 retailers. 

Before diving into the activation process, take a moment to check your Sim card packaging. Ensure you have all the necessary information at hand, such as your Sim card number (ICCID) and any activation codes provided. These details will be crucial in the following steps.

Also, when you order a Sim card from a provider, it'll usually send a 3-in-1 Sim, so if your phone supports a smaller size, you'll be able to break it down to the correct size for your phone. The latest smartphones will usually work with a nano Sim. There are three main types and sizes of Sim card available, which fit specific devices. These are:

  • Standard Sim card (15mm x 25mm)
  • Micro Sim card (12mm x 15mm)
  • Nano Sim card (8.8m x 12.3mm)

If you've ordered a Sim online, for example, though our Cheap Mobile Finder, your allowance (minutes, text and data) will be preloaded onto the Sim itself, so you won't need to do anything once it has been activated.

Want to keep your number?

If you want to keep your number, Ofcom's 'text-to-switch' rules makes it even easier to ditch your network.

  • Request a switching code by text. Simply text 'PAC' for free to 65075 on any network and you'll be sent your 'porting authorisation code' (PAC) immediately via text so you can keep your number. To get a new number, text 'STAC' to 75075.

    The text from your provider must include important info such as any exit penalties, outstanding handset costs or credit balances.

  • Then give the PAC to your new provider within 30 days. You'll then be switched, usually within one working day. You won't need to contact your old provider again.

How to activate your new Sim card

It's relatively easy to do, usually it's just a case of putting it in to your phone and it'll work straightaway. But if you have a phone that was purchased prior to 2021, there's a chance it could be locked to a specific network, meaning a new Sim with a different network won't automatically work. Don't worry though, you can usually easily unlock your phone for free. Here's how to activate with most of the top Sim providers...

Activating your O2 Sim card

If you've joined O2 as a pay monthly customer, there's no need to activate as you can pop the Sim card into your phone and it'll work straightaway. The process is slightly different if you're a pay-as-you-go customer as it requires you to top up before it starts working.

If you want to keep your number and move it to O2, you'll need to enter your temporary O2 number and then use your current network's PAC. It takes one working day to do the transfer.

Activating your EE Sim card

With EE, you only need to activate your Sim if you've upgraded your contract and have been sent a new Sim, or ordered a new one because your old one no longer fits your device (Sim swap).

For anyone else, it's just a case of popping the Sim into your device and it'll work straightaway.

If you want to transfer your number to EE, you can fill out a quick form on its site. You'll need your temporary EE number and PAC to hand. Transfers will complete in one working day.

Activating your Vodafone Sim card

To active your Sim with Vodafone, insert the Sim in your phone and it'll work straightaway. If you're a pay-as-you-go customer, you'll also need to top it up first before you can use it.

You can then register for a My Vodafone account, so you can access its Very Me Rewards.

Activating your Three Sim card

Once you've inserted your Three Sim, you'll need to activate it via that dedicated page. You'll need your temporary Three number and the 19-digit Sim number (ICCID), which you'll find on the Sim card pack itself. Once submitted, it'll be activated within a couple of hours.

If you want to keep your number, you can enter the phone number you wish to keep and your PAC on its switching page and Three will switch it within one working day.

Activating your Giffgaff Sim card

To activate your Giffgaff Sim, you'll need to follow the step-by-step instructions on Giffgaff's website. Simply enter the activation code printed on your new Sim (it’ll be six or 13 digits long).

Activating your iD Mobile Sim card

If you're a new customer to iD Mobile, your Sim card will arrive already activated, so you just need to insert it into your phone.

If you've previously lost your Sim and have received a replacement, you will need to activate your Sim.

If you've take out an upgrade with iD Mobile, it says a Sim swap isn't necessary and you'll be able to continue using your current Sim card.

Activating your Smarty Sim card

You can activate a Smarty Sim by going to Smarty's activation page.

If you’re an existing customer, you’ll need to log in and follow the onscreen instructions. If you’re new to Smarty, just enter the last 12 digits of the number on the back of your Sim (the numbers following 8944200).

Activating your Voxi Sim card

To active your Voxi Sim, just enter the numbers located on the Sim card itself (the numbers following 00030) into Voxi's activation page, then pick the plan you want to use.

If you want to move your number to Voxi, either enter your PAC when ordering your Sim, else you can enter this once you've signed up via Voxi's online account

Activating your Lebara Sim

With your new Lebara Sim, insert the Sim into your phone and it'll work straightaway.

If you want to move your number to Lebara, enter your temporary Lebara number on its switching page, followed by your PAC. It'll take one working day, or you can select a date. 

Activating your Lycamobile Sim

With your new Lycamobile Sim, just insert the Sim into your phone and it'll work straightaway.

If you want to move your number to Lycamobile, you'll need to fill in its online porting form and it'll process this within two working days.

Activating your Asda Mobile Sim card

With your new Asda Mobile Sim, insert the Sim into your phone and it'll work straightaway. You'll get a text to confirm it's been activated.  

If you want to move your number to Asda Mobile, you'll need to register for an online account. You can then enter your PAC and it'll transfer your number within one working day.

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