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How to change your SIM card and keep your number the same

black phone with sim card out and removal tool nearby - how to change sim card but keep same number

Switching networks should be a painless process and with these simple tips you can hold on to your old phone number when you get a new SIM

There are plenty of reasons to switch networks – maybe you’ve found a better SIM deal, perhaps you want a new device that your provider doesn’t offer or it could be that you just can’t get the mobile signal you need on your current network. However, switching can seem daunting and most people’s main worry is whether they can keep their old phone number.

Well, good news. In the UK, there are rules in place that ensure you can hold onto your existing number when changing providers. And generally, the best mobile networks make this process really simple. In this article, we’ll tell you everything you need to know to make the switch as easy as possible. As part of our research, we spoke to Cristina Luna-Esteban, director of consumer policy at Ofcom, to ensure that our information is as accurate and up-to-date as possible.

What does a SIM card do?

Before we get into the details, it might be helpful to understand the function of a SIM card. SIM stands for Subscriber Identity Module and, in normal use, your phone number will be tied to your SIM card. So, if you take your SIM and put it in your friend’s phone, for example, then your friend’s phone will receive phone calls to your number and, similarly, any calls or data usage from that phone will come out of your allowance. At least, until you take that SIM back.

red sim cards scattered on grey background - how to chnage sim card but keep same number

Everything else that’s stored on your phone – from your photos, videos and apps to your browsing history and messages – will remain on your phone. The only exception might be your contacts, since a SIM card has a limited amount of storage and you can choose to save contacts to it. However, usually, your contacts will be stored on your phone, rather than the SIM.

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Will I lose my number if I change my SIM card?

Changing your SIM card doesn’t mean that you have to change your phone number. The number is assigned to you as part of the activation process so, as long as you’ve notified your previous provider, you should be able to transfer across the number with ease.

Cristina Luna-Esteban, director of consumer policy at Ofcom, told us: “If you’re unhappy with your mobile phone provider, then it’s easy to start the switching process. Our rules mean that you can keep your number by simply sending a quick, free text.”

She adds: “The ‘text-to-switch’ process gives you control over how much contact you have with your provider.” She continues, “you can text ‘INFO’ to 85075 to find out if you’re still in contract, and if you have to pay any charges to end your contract early.”

What is a PAC?

PAC stands for Porting Authorisation Code and it allows you to keep your number when switching network providers. Essentially, requesting a PAC code notifies your old provider that you’re leaving and that it needs to make your phone number available to the new provider.

A PAC code is provided free of charge, as per Ofcom rules, but you should check if you’re still in contract as you could be charged a substantial exit fee if you terminate your contract early – as mentioned earlier, you can quickly check your current contract status by texting “INFO” to 85075.

Your PAC code is typically valid for 30 days and if it isn’t used in that period, you’ll remain with your current provider and continue to be charged by them. You can request another PAC code if it expires before you switch.

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How to get a PAC code

The quickest and easiest way to get hold of your PAC code is using text-to-switch. Text “PAC” to 65075 and you should receive your PAC code as a reply in a few minutes.

woman with stripy shirt using smartphone - how to change sim card but keep same number

If, for some reason, you would prefer not to use text messaging, you can also get a PAC code by calling your network provider. We’ve listed contact information for some of the most popular UK networks below; if your provider isn’t listed, check the company website or your mobile bill.


  • Call 150 from your EE phone
  • Call 07953 966 250 from any phone


  • Call 333 from your Three phone
  • Call 0333 338 1001 from any phone


  • Call 191 from your Vodafone mobile
  • Call 0333 304 0191 from any phone


  • Call 202 from an O2 phone
  • Call 0344 809 0202 from any phone

Sky Mobile

  • Call 03300 412 524 from any phone

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How to transfer your mobile number

Here’s a step-by-step guide to switching SIM cards without losing your number.

1. Request your PAC code

Text “PAC” to 65075 and you’ll receive the code within minutes. If you don’t want to send a text, then use the alternative methods listed above.

2. Contact your new network provider

You’ll need to give this PAC code to your new network provider, so it can transfer your number and set up your new SIM card. This normally takes about one working day so, in the meantime, you’ll want to keep your old SIM card installed to stay connected. The old SIM will continue to work until the transfer is complete.

3. Switch to your new SIM card

Your new service provider should get in touch to notify you that your number has been transferred. Then you can insert the new SIM card and begin using it – you’ll need a SIM eject tool to access the SIM card tray on most modern phones. Once you’ve inserted the new SIM, make a test phone call to ensure everything is working as expected.

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Will I lose my contacts if I switch SIM?

If you’re keeping the same phone

Most people’s contacts are saved to their phone, rather than their SIM card. As such, if you’re keeping the same device, then you likely won’t see a difference when you switch SIM. However, if you’ve chosen to save your contacts to your SIM, then you’ll need to move them to the phone before switching out your SIM card.

The quickest way to check where your contacts are saved is by removing your current SIM card and heading into your contacts. If they still appear as usual, they’re saved to the phone and you have nothing to worry about. If they disappear, you’ll need to move them over.

The process differs slightly between devices. If you’re on Android, you’ll typically need to open Contacts app, go into the Settings menu and look for Import or Export Contacts. Then you can move the contacts from your SIM card to your phone.

On an iPhone, head into Settings, then choose Contacts and tap Import SIM Contacts. Once that’s done, the contacts will be stored on the phone.

If you’re switching phone and SIM card

man opening new phone on grey background - how to change sim card but keep same number

If you’re switching devices, having picked up a new smartphone and a new SIM card at the same time, the above steps still apply as you’ll need your contacts to be stored on your old phone.

Once the contacts are stored on your old phone, we recommend using your new phone’s migration assistant to transfer the contacts over. This should appear by default as part of the set-up process on any new phone, so just follow the onscreen instructions and you’ll be good to go.

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