Switching from Three to O2? It's a straightforward process to keep your existing phone number.

Step 1: Get a PAC Code from Three

If you’d like to move your phone number from Three to O2, the first step is getting your Porting Authorisation Code (or PAC Code) from Three.

There are three ways to get a PAC Code from Three:

  1. Online: You can get a PAC Code from Three by logging in to the My3 Account website.
  2. By Text Message: You can get a Three PAC Code sent to you via SMS text message. Text PAC followed by your date of birth in DDMMYY format to 65075 to receive a PAC Code from Three.
  3. By Phone: You can get a PAC Code by calling Three. To do this, call them on 333 using your Three handset. Alternatively, dial 0333 338 1001 from any other phone. You'll need to call during Three's opening hours (Monday-Friday 8am-8pm, Saturday 9am-6pm, Sunday 9am-6pm).

Here are some key things to know:

  • The PAC Code from Three should consist of six numbers with HTG at the start (e.g. HTG 123 456).
  • Your PAC Code is valid for 30 days. If you don't use it during this time, the PAC Code will expire and you'll need to request a new one.
  • You shouldn't close your account at Three: it'll be closed automatically when your phone number is transferred to O2.

Still in contract with Three? If so, you may need to pay an early exit fee on your bill from Three. To find out how much this would be, text INFO followed by your date of birth in DDMMYY format to 87075.

Don’t want to keep your Three phone number? You can switch to O2 without taking your phone number with you. If you'd like to do this, get a STAC Code from Three instead.

Three STAC Code (Leave Three Without Keeping Your Number)

If you’d like to leave Three without keeping your phone number, you’ll need to request a STAC Code rather than a PAC Code. There are three ways to get a STAC Code from Three:

  1. Online: You can get a STAC Code from Three by logging in to the My3 Account website.
  2. By Text Message: You can get a Three STAC Code sent to you via SMS text message. Text STAC followed by your date of birth in DDMMYY format to 75075 to receive a STAC Code from Three.
  3. By Phone: You can get a STAC Code by calling Three. Call them on 333 using your Three handset. Alternatively, dial 0333 338 1001 from any other phone. You'll need to call during Three's opening hours (Monday-Friday 8am-8pm, Saturday 9am-6pm, Sunday 9am-6pm).

Once you’ve gotten your STAC Code from Three, the rest of the process for joining O2 remains the same.

Step 2: Order your new phone or SIM card from O2's website

You should now order your new phone or SIM card using the O2 website. Please select the type of tariff you're intending to move to:

If you're looking for a SIM card from O2, the following deals from £10/month are currently most popular:

NetworkMinutesTextsDataMonthly
Cost
O2UnlimitedUnlimited5GB£10.00
24 months
O2UnlimitedUnlimited12GB£12.00
24 months
O2UnlimitedUnlimited30GB£16.00
24 months
O2UnlimitedUnlimited150GB£20.00
24 months
O2UnlimitedUnlimitedUnlimited£25.00
24 months

For a full list of available tariffs and the latest O2 deals, please refer to this page on O2's website.

Alternatively, if you're getting your O2 plan from a reseller, tap on their logo for more information:

O2 will assign you with a temporary phone number during the transition process. This will allow you to test out the service before you finally transfer your phone number to O2.

Step 3: Give the PAC Code to O2

Once your new phone or SIM card arrives from O2, switch it on and make sure everything's working properly. If, for whatever reason, you need to return or change the handset or SIM card, it's best to do this before transferring your phone number.

Once you're happy to continue with the phone number transfer, contact O2 and provide them with your PAC Code from Three.

Your PAC Code should be entered on O2's online form. You can also provide your PAC Code to O2 over the phone:

If you're joining O2 Pay Monthly, you can submit your PAC Code by calling 202 on your O2 handset. Alternatively, call 0344 8090202 from any other phone.

Alternatively, if you're joining O2 Pay As You Go, submit your PAC Code by calling 4445 (0344 8090222 if you're calling from another network).

If you have a STAC Code from Three rather than a PAC Code, this can be provided to O2 in the exact same way.

Providing your PAC Code to O2
The PAC Code should be submitted through a form on O2's website.

Remember:

  • You must provide the PAC Code to O2 within 30 days of it being issued by Three. If the PAC Code has already expired, you'll need to return to step 1 and request a new PAC Code from Three.
  • Three Pay As You Go customers: Try to use up your remaining credit as it can't be transferred to O2.

Step 4: Phone Number Transferred (Next Working Day)

Once you've provided a PAC code to O2, your phone number transfer will normally be scheduled for the next working day (Monday to Friday only, excluding English bank holidays).

On the day of the transfer, you'll momentarily lose coverage on both mobile networks. When this happens, restart your handset on O2. You should find that the O2 phone or SIM card will now associated with your original phone number.

  • If you see an error message (e.g. "SIM card registration failed"), this means it's time to restart your phone.
  • Once the phone number has been transferred to O2, your account on Three will automatically be closed. You'll receive a final bill from Three for any outstanding charges.

Get the Latest Deals from O2 →

Any Other Questions?

In case of any problems during the transfer of your phone number, you should contact your new mobile network (O2) with details of the problem.

If you have any other questions on using a PAC Code, please see my in-depth guide to transferring your phone number between networks. You can also read the comments below from other visitors to this website.

← Full Article: "PAC Codes - How to transfer your mobile number when switching networks"

Your Comments 1,935 so far

We'd love to hear your comments on transferring a phone number from Three to O2. The comments below are from people who've made the same transfer. You can add your own comments here.

To view all 1935 comments about transferring a phone number, please visit the main PAC Code article.

  • Hi

    I transferred a number from a payg 3 (three) account to O2 Contract. Its been 10 days now and still no incoming calls. O2 are saying they have requested the porting files again and are waiting and cant do anything until they receive these.

    O2 made me change my SIM/disconnect me for 4 hours, unaccountable number of problem solving requests still no joy.

    Any advise?

    THANKS

  • Hi Ken, I am a little bit confused and found on the internet you would give me a good & helpful advice.

    I am on the last month of contract with THREE. I wanted to upgrade and stay with THREE but they do not have a handset which I want to upgrade to. I am deciding to finish this contract and do not upgrade but I want to keep my current telephone number. I know that to go to pay as you go I just need to speak to THREE's advisor that I want to just move to pay as you go.

    The thing is that I want to get a contract with O2 now because they have exact handset that I want. Confusion starts now because I have no idea how to transfer my number from contract with THREE to contract with O2. What I have found is that there are 3 steps of this ! First : I need to get my number transferred to pay as you go at THREE and then obtain a PAC and transfer my number to O2 pay as you go and then to O2 contract ….. Is this right??

    please help me !! thanks so much

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