TL;DR
- A STAC (Service Termination Authorisation Code) cancels your mobile contract without transferring your number to a new network.
- Text STAC to 75075 to receive your code instantly; providers must supply it within a few seconds under Ofcom rules.
- Use a STAC when you are getting a new number on a new network, not when you want to keep your existing number.
- Your phone number is permanently relinquished when you use a STAC; it cannot be recovered once the cancellation completes.
- Cancellation must complete by the end of the next working day after your new provider submits the STAC code.
What the STAC Code Is and How It Differs from a PAC
A Service Termination Authorisation Code, universally known as a STAC, is the mechanism by which a UK mobile customer closes their account with their current network without taking their phone number with them. It was introduced alongside the PAC (Porting Authorisation Code) as part of Ofcom's 2019 overhaul of mobile switching, which was designed to make leaving a network as frictionless as possible regardless of whether the customer wished to keep their number or not.
The key distinction is straightforward: a PAC transfers your number to a new network; a STAC terminates your service and releases the number back to the old network, which will eventually reassign it to another customer. If you are moving to a new network and are entirely happy to start fresh with a different phone number, a STAC is the correct code to use. If you want to carry your existing number across, you need a PAC instead.
When to Use a STAC Instead of a PAC
Several practical situations call for a STAC rather than a PAC. The most common is moving to a new network on a new SIM-only deal or handset contract where you intend to use the new number provided by that network. This often applies to people setting up a dedicated work number, starting fresh after a relationship breakdown, or simply those who are not attached to their current number and do not wish to go through the additional steps of number porting.
A STAC is also appropriate when cancelling a secondary SIM, a mobile broadband or MiFi account, or a data-only contract where there is no meaningful phone number to preserve. In these cases using a STAC avoids any confusion about porting a number that you never had reason to retain. It is worth emphasising that choosing a STAC is irreversible with respect to your old number; once the cancellation completes you cannot reclaim it.
How to Request a STAC Code
The simplest route is to text the word STAC to 75075 from the mobile you wish to cancel. This free, Ofcom-mandated service operates across all major UK mobile networks and returns your STAC code by text message within seconds. The return message includes the code itself, its 30-day expiry date, and information about any outstanding contract balance or early termination fees, so you have the full financial picture before you hand the code to your new provider.
You can also request a STAC by calling your provider's customer services or, where the option is available, through their online account portal or app. Providers are required by Ofcom to supply the code immediately when requested by text, or within two hours during business hours by other methods. They are prohibited from using the request as an opportunity to apply undue retention pressure. If an agent attempts to withhold the code or makes the process significantly difficult, this is a potential breach of Ofcom's General Conditions and can be reported as a complaint.
| Feature | PAC Code | STAC Code |
|---|---|---|
| Purpose | Transfer number to new network | Cancel service; relinquish number |
| Text request number | 65075 | 75075 |
| Phone number retained? | Yes — moves with you | No — permanently released |
| Code expiry | 30 days | 30 days |
| Ofcom completion deadline | End of next working day after submission | End of next working day after submission |
| Typical use case | Switching networks, keeping same number | Getting a new number, closing an account |
What Happens to Your Number When You Use a STAC
When your STAC code is submitted by your new provider (or by you, if you are simply cancelling without moving to another network), your current provider begins the process of terminating your account. Your phone number is removed from your account and returned to the number range managed by that operator. Under numbering plan conventions overseen by Ofcom, the number will sit dormant for a quarantine period before being reassigned to a new customer. This quarantine exists to prevent calls and texts intended for you from reaching a stranger immediately after the switch.
Once released, there is no mechanism to reclaim your old number. If you realise after the fact that you needed to keep it, you would have to contact your old provider and request the number back, and even then reclaim is only possible if the number has not yet been reassigned and if the provider agrees — there is no regulatory right to a reinstatement. This is why confirming you genuinely do not need the number before using a STAC is important.
Cancellation Timelines Under Ofcom Rules
The timeline for STAC-based cancellation mirrors that for PAC-based porting. Once your new provider (or you directly, where the network accepts a consumer-initiated STAC) submits the code, cancellation must complete by the end of the next working day. If you are moving to a new network at the same time, the new account activation and the old account cancellation are coordinated so that there is no extended period without a working SIM.
If you are cancelling without moving to another provider — for example closing a secondary SIM you no longer need — the process works slightly differently. You would obtain your STAC and submit it directly to your current provider, who must then close the account within the same one-working-day window. Your current provider should confirm the cancellation date and issue a final bill covering usage up to that date. Any direct debits associated with the account should be cancelled promptly by the provider, and you should also cancel them with your bank as a precaution.
Outstanding Charges and Early Termination Fees
The STAC text message you receive when requesting your code includes a statement of any amounts you owe. If you are still within a fixed-term contract (for example, a 24-month handset agreement with months remaining), your provider will calculate an Early Termination Fee (ETF). Under Ofcom's rules, ETFs must be based on the remaining monthly subscription charges less a reduction to account for costs the provider no longer incurs, such as network costs associated with serving you. Providers cannot simply charge the full face value of all remaining monthly bills without applying this reduction.
If you are on a rolling monthly contract with no fixed term, there should be no ETF, though you may owe the current month's charge if you are mid-cycle. Checking the exact figures stated in the STAC text before proceeding means you will not be surprised by the final bill. Any disputed charges after cancellation should be raised as a formal complaint with the provider, and unresolved disputes can be taken to an Ofcom-approved Alternative Dispute Resolution scheme.
What this means in practice
James, a freelancer in Leeds, has been running two SIM cards: a personal number he has held for ten years, and a work number he took out 18 months ago on a 24-month contract. He has decided to consolidate to one number and no longer needs the work SIM. He texts STAC to 75075 from his work handset. The return message confirms his nine-character STAC code, a 30-day expiry, and states he owes six months of remaining subscription at a discounted ETF rate totalling approximately £72 — the reduced figure rather than the full face value of the remaining bills. He proceeds, submits the STAC to his provider, the account closes the following morning, and the direct debit is cancelled on his next bank statement. His personal number is entirely unaffected throughout.
Related Guides
How we verified this
This article is based on Ofcom's published guidance on switching and the text-to-switch service (ofcom.org.uk), the requirements set out in General Condition C8 of Ofcom's General Conditions of Entitlement, and Ofcom's guidance on Early Termination Fees for consumer mobile contracts. No operator-specific data or proprietary pricing has been used.
Disclaimer: Kaeltripton.com is an independent UK editorial publisher. We are not regulated by Ofcom or the FCA and we do not sell or arrange mobile services, insurance, or financial products. This content is for general information only and is not legal, financial, or technical advice. Rules, prices, and operator policies change. Verify the current position with Ofcom, GOV.UK, the ICO, or your provider before acting. ICO registered ZC135439. Last reviewed: 2026-06-05.
Frequently Asked Questions
What is a STAC code?
A STAC (Service Termination Authorisation Code) is a nine-character alphanumeric code that authorises your current mobile provider to close your account. Unlike a PAC code, which transfers your number to a new network, a STAC simply ends your contract and releases your phone number. It is part of the Ofcom-mandated text-to-switch system introduced in July 2019 to make mobile switching faster and easier for consumers.
When should I use a STAC code?
Use a STAC when you want to cancel your current mobile contract and do not intend to keep your phone number. Common situations include getting a brand-new number on a new network, closing a secondary or data-only SIM you no longer need, or cancelling a mobile broadband account. If you want to take your existing number to a new provider, you need a PAC code rather than a STAC.
How do I get a STAC code?
Text the word STAC to 75075 from the mobile you wish to cancel. Your provider must return the code by text within seconds under Ofcom rules, along with your code's 30-day expiry date and a summary of any outstanding balance or early termination fees. You can also request a STAC by calling your provider or via their app or website, though the text method is fastest and providers must respond within two hours by non-text means during business hours.
What happens to my phone number if I use a STAC code?
Your phone number is permanently relinquished when a STAC cancellation completes. The number is returned to your former provider's number range, placed in a dormancy period under Ofcom's numbering plan rules, and eventually reassigned to a new customer. There is no regulatory right to reclaim the number once released. If retaining your number matters to you, request a PAC code instead of a STAC.
How long does cancellation with a STAC code take?
Under Ofcom's General Condition C8, cancellation must complete by the end of the next working day after the STAC is submitted to your provider. In practice, most accounts close mid-morning on the next working day. Your STAC code is valid for 30 days from the date it is issued, so you have time to arrange your new service before triggering the cancellation.
