Switching from T-Mobile to Three? It's a straightforward process to keep your existing phone number.

Step 1: Get a PAC Code from T-Mobile

If you’d like to move your phone number from T-Mobile to Three, the first step is getting your Porting Authorisation Code (or PAC Code) from T-Mobile.

There are two ways to get a PAC Code from T-Mobile:

  1. By Text Message: You can get a T-Mobile PAC Code sent to you via SMS text message. Text PAC to 65075 to receive a PAC Code from T-Mobile.
  2. By Phone: You can get a PAC Code by calling T-Mobile. To do this, call them on 150 using your T-Mobile handset. Alternatively, dial 020 7362 0200 from any other phone. You'll need to call during T-Mobile's opening hours (Monday-Friday 8am-8pm, Saturday 8am-6pm, Sunday 8am-6pm).

Here are some key things to know:

  • A PAC Code is 9 digits long and follows the format ABC 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 T-Mobile: it'll be closed automatically when your phone number is transferred to Three.

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

T-Mobile STAC Code (Leave T-Mobile Without Keeping Your Number)

If you’d like to leave T-Mobile without keeping your phone number, you’ll need to request a STAC Code rather than a PAC Code. There are two ways to get a STAC Code from T-Mobile:

  1. By Text Message: You can get a T-Mobile STAC Code sent to you via SMS text message. Text STAC to 75075 to receive a STAC Code from T-Mobile.
  2. By Phone: You can get a STAC Code by calling T-Mobile. Call them on 150 using your T-Mobile handset. Alternatively, dial 020 7362 0200 from any other phone. You'll need to call during T-Mobile's opening hours (Monday-Friday 8am-8pm, Saturday 8am-6pm, Sunday 8am-6pm).

Once you’ve gotten your STAC Code from T-Mobile, the rest of the process for joining Three remains the same.

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

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

If you're looking for a SIM card from Three, the following deals from £5/month are currently most popular:

Network Data Monthly Cost
Three
  • Unlimited mins
  • Unlimited texts
3GB
data
£5.00
per month
24 month contract
Monthly cost will rise each April by £1
See deal  
Three
  • Unlimited mins
  • Unlimited texts
12GB
data
£6.00
per month
12 month contract
Monthly cost will rise each April by £1.25
See deal  
Three
  • Unlimited mins
  • Unlimited texts
30GB
data
£7.00
per month
12 month contract
Monthly cost will rise each April by £1.25
See deal  
Three
  • Unlimited mins
  • Unlimited texts
250GB
data
£14.00
per month
12 month contract
Monthly cost will rise each April by £1.50
See deal  
Three
  • Unlimited mins
  • Unlimited texts
Unlimited
data
£22.00
per month
24 month contract
Monthly cost will rise each April by £1.50
See deal  

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

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

Three 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 Three.

Step 3: Give the PAC Code to Three

Once your new phone or SIM card arrives from Three, 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 Three and provide them with your PAC Code from T-Mobile.

Your PAC Code should be entered on Three's online form. Alternatively, you can give the PAC Code to Three by calling 333 on your Three handset. You can also call 0333 338 1001 from any other phone.

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

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

Remember:

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

Step 4: Phone Number Transferred (Next Working Day)

As long as you've submitted your PAC Code to Three before 5pm, your phone number transfer will normally be scheduled for the next working day (Monday to Friday only, excluding English bank holidays). After 5pm, you'll need to wait one extra working day for your number to be transferred.

On the day of the transfer, you'll momentarily lose coverage on both mobile networks. When this happens, restart your handset on Three. You should find that the Three 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 Three, your account on T-Mobile will automatically be closed. You'll receive a final bill from T-Mobile for any outstanding charges.

Get the Latest Deals from Three →

Any Other Questions?

In case of any problems during the transfer of your phone number, you should contact your new mobile network (Three) 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 1,966 so far

We'd love to hear your comments on transferring a phone number from T-Mobile to Three. The comments below are from people who've made the same transfer. You can add your own comments here.

To view all 1966 comments about transferring a phone number, please visit the main PAC Code article.

  • Andy said:

    Hi Ken,

    Thanks again for the useful site.

    My billing period with T-Mobile (EE) runs from 12th to 12th (now out of my 2 year contract so have defaulted to a 12 month rolling contract). Should I place my order for a 3 SIM on, say, the 9th or 10th so that I minimize the amount of overlap of the 2 contracts? I imagine I would have to pay for a whole month even if I only use part of it?

    Rgds,
    Andy

    • Ken replied:

      Hi Andy,
      Thanks for your comment. As your 24 month contract has now ended with T-Mobile, you’ll be placed automatically on a 1-month rolling contract (not 12 months as you mentioned in your comment). You’ll need to give 30 days notice before ending the contract so I’d recommend doing this as quickly as you can. Ask them for a PAC Code whilst you’re on the phone. You can then order a SIM card from Three. You can schedule the phone number transfer towards the end of the 30 days to minimise contract overlap. Don’t worry about ending your contract in the middle of a billing month (the charges for the final month are pro-rated based on the number of days you’ve been using the SIM card for).
      Hope this helps!
      Ken

  • James Williams said:

    Hi Ken

    I’ve got myself a new 30-day rolling contract from 3, and have my PAC code from T-Mobile for my old 30-day rolling contract.

    I’m just wondering when the best time to commence the transfer with 3 and use the PAC? My billing date with T-Mobile is the 18th, and I am just unsure when would be the best time to use my PAC, bearing in mind it has 30 days before expiration.

    I only want to make sure that my cancellation won’t be too costly.

    • Ken replied:

      Hi James,

      Thanks for the comment! I think the best thing to do would be to use your PAC Code as soon as possible. At present, you’re paying for both contracts at the same time. Once the PAC code has been used, you’ll only need to pay for the SIM Only deal on Three. For the number transfer, you should ideally choose a time period when you’re unlikely to receive important calls/texts.

      Hope this helps,

      Ken

  • fungie said:

    I am moving provider for a better deal. I was with tmobile and intend to move to 3mob. I have served my cancellation notice and have requested a PAC code and tmobile are saying I have to wait a further 30 days if I want this code. I am confused and feel cheated!! Help

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