Switch from O2 to Giffgaff and keep your number using a PAC code

Last Updated: 29th July 2025

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Are you thinking about leaving O2 and switching to Giffgaff? Then you're in the right place! Switching networks and keeping your number in 2025 is simple and easy thanks to Ofcom's policy changes.

We've put together a quick and easy to use switching guide. Our guides allow you to select the network you wish to switch to and from, and you will be given a step by step guide on how to keep your number and move to a new SIM Only Deal.

It is worth noting that if you wish to join Giffgaff and get a new number then you can use a STAC code in order to get a new number and will cancel your existing contract.

Joining Giffgaff and leaving O2

Joining Giffgaff and transferring your number from O2 is a simple process and usually takes no longer than 1-2 working days.

The process which will go through in more detail below involves requesting a PAC code from O2 and handing it to Giffgaff.

You can either hand the PAC code over to Giffgaff during the ordering process or after you have received your new SIM card or eSIM has been activated.

1. Request a PAC code from O2

Switching from O2 and keeping your current phone number is easy. There is no need to commit a new number to memory or update all your contacts!

Here is how to get your PAC (Porting Authorisation Code) from O2:

• Text: From your O2 phone, text "PAC" to 65075. You will receive a text back with your code within 60 seconds. This is a free service from Ofcom (the UK's communications regulator).
• Online: Log in to your O2 account online ("My O2") and request your PAC code.
• Phone: Call O2 customer service on 202 from your O2 phone or 0344 809 0202 from another phone.
  • Their customer support is open;
    • Monday - Friday: 8am - 9pm
    • Saturday: 8am - 8pm
    • Sunday: 8am - 6pm
• In-store: Pop into your nearest O2 store and request to leave.

Your PAC code is valid for 30 days, so you can request it before you get your new SIM card. You can retrieve it from your O2 account or by calling O2 if you lose it.

If you want a new number and do not wish to keep your current number, you will need to request an STAC code instead of a PAC code. Text "STAC" to 75075 to get your STAC code.

2. Order a SIM only deal from Giffgaff

If you haven't yet ordered your new Giffgaff SIM Only deal, you can use our free comparison engine, which will show you the cheapest Giffgaff deals available on the market.

Compare Giffgaff SIM Only Deals

If you already have your new SIM Card, feel free to skip to step 3 of this article

During the ordering process you may be given the opportunity to share your PAC code from O2 to Giffgaff, if you choose this option then the number transfer process will start once your new sim card arrives and you activate it in by putting it in your phone and turning it on, this also means you can skip to step 4 of this article if you wish!

If you are not given the opportunity to hand over your PAC code when ordering then there's no need to panic. Once your new sim card from Giffgaff has arrived, just continue to step 3 of this article.

It is also worth calling out that it doesn't matter if you are able to hand over your PAC code from O2 whilst buying your new sim from Giffgaff or not it's just slightly more convenient but the outcome is the same!

3. Give the PAC code to Giffgaff

Once you have your PAC code, follow these steps to give it to Giffgaff:

• Activate your Giffgaff SIM card: If you have not already, activate your Giffgaff SIM card.
• Find the number transfer link: After activating your SIM, Giffgaff will provide you with a link to transfer your number.
• Enter your PAC code: Follow the link and enter your PAC code when prompted.

Giffgaff will then handle the transfer of your number.

Important Notes:

• If you want a new Giffgaff number and don't need to keep your current number, request a STAC code instead of a PAC code from your current network.
• If you don't use your PAC code within 30 days, you will need to request a new one.
• If you can't find your Giffgaff activation code, you can activate your SIM using the serial number (found on the back of the SIM card).

4. Wait for your number transfer to Giffgaff to complete

That's it you've done the hard work, now sit back and relax. Giffgaff will notify O2 of your intention to leave and take your mobile number to Giffgaff.

The number transfer process will usually take 1 to 2 working days. After this time your O2 mobile number will be working on the Giffgaff SIM card.