Switching mobile contracts

upgrading your phone

In the past, the process for switching from one mobile phone company was a chore, you had to spend ages on the phone in a queue to an agent that would try to sell you a better deal on your mobile phone contract instead of letting you move to a different network, thankfully this has changed to a code you send from your phone as a text.

PAC code

Mobile phone numbers are transferred between network operators these days through a process known as Local Number Portability, and to transfer your number from one operator to another, it’s a simple process of applying for a Port Authorisation Code or PAC code.

You can do this by texting PAC to 65075. You will receive in return a text message with a 9 character alphanumeric code that is valid for 30 days. If you are in an active contract, you may have to pay a termination fee, especially if that contract involved the operator providing you a mobile phone or tablet as part of the contract.

Other operators have different number you can use to get this PAC code. You give your next operator this code and your number is ported over to your new account, be that a Pay as you Go or a contract.

It takes 1 working day for your existing provider to end your contract and port your number to the new provider, and often in that time your new provider will have issued you a SIM card. However, postal delays may mean you are without a phone service for a day or so while your SIM card is in the post.

Number (Customer Services)
0800 800 150
07953 966250
No telephone number
iD Mobile
0333 003 7777
020 7031 0791
0344 809 0222
080 0013 2632
No telephone number
0345 301 4455
0345 600 0789
No telephone number


Just like a PAC code is for porting your old number to your new provider,a Subscriber Termination Authorisation Code or STAC code is a request to terminate the current number. The process for a STAC code is similar, you text STAC to 75075. You will receive a response in about 1 minute from your existing provider and your 9 alphanumeric character code will be generated and is valid for 30 days.

If you are receiving nuisance calls or texts however, follow the advice from Ofcom here.


If you want to find out about any charges you may incur on your contract if you want to switch to a new provider, text INFO to 85075. Your current provider will tell you what the costs are to move, whether you are in a running contract or if the contract has lapsed.

PUK Code

If you acquired your phone through a contract (which is often a lot cheaper than buying the phone outright, but then you are effectively taxed on the monthly contract fee) you need a Personal Unlock Key or PUK code, often called a Network Unlock Code – NUC or Personal Unlock Code – PUC. Each provider has a different way to obtain this code.


You can set a PIN on your SIM card that prevents the SIM from being switched to another phone and prevents calls, texts and mobile data from being used on that SIM without the correct PIN. If you enter the incorrect PIN 3 times, the SIM will be blocked. You must then acquire a PUK code to unlock the SIM PIN. If the PUK code is entered incorrectly 10 times, the SIM will wipe itself. SIM PIN codes are not that common with the advent of smart phones, but you can still use them to prevent someone stealing your phone and using your SIM to make calls, however most thieves steal phones to sell them on for drugs.

Often if there is a SIM PIN set, it is printed on the SIM tray that came with your SIM, along with the PUK code.


In my case, my wife wanted to pool all our numbers under one contract with BT, which meant savings on the BT bill to have a family plan, however BT kept increasing the price of the plans without offering improvements in return, and I couldn’t see how much data I had left in my plan.

If you have a combined plan, you can’t use the PAC code system, you have to have the account holder contact customer services and then you will receive the PAC code via a text to your phone.

Additionally, since as soon as the PAC code is given to the new provider, your phone’s SIM is deactivated 1 day after the PAC code is received, although in reality, it’s after 5pm of that day so your phone loses service in the evening when you might need it the most, like the mobile data for a sat nav or when a family member tries to call you urgently.

Additionally, any call routing you may have on your number ceases with the contract, so even if you divert on no answer to voicemail, the number responds with “out of service”.

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