How to Keep Your UK Mobile Number When Switching Provider
Switching your mobile network in the UK has never been easier, and thankfully you no longer need to put up with poor signal, expensive monthly bills, or slow data speeds just because you don’t want to lose your mobile number. Whether you’re moving from a major provider like EE, O2, Vodafone, or Three, or switching to a smaller MVNO such as giffgaff, VOXI, Lebara, or SMARTY, you can keep your existing number in just a day or two — without complicated paperwork or awkward phone calls.
In fact, you can usually transfer your number simply by sending a single text message. This guide walks you through every step, explains what to expect during the transfer, and offers a few insider tips that UK users often miss when switching providers.
What You Need Before You Transfer Your Number
Before starting the number-switch process, make sure you have the essentials ready. Fortunately, the requirements in the UK are minimal:
- Your current mobile number (the one you want to keep)
- Your existing SIM still working in your phone
- A new SIM card or eSIM from your new network
- A PAC or STAC code (explained below)
You do not need account numbers, passwords, or any personal documents. The UK switching system was designed so customers can move networks quickly and without pressure.
PAC vs STAC Codes — What’s the Difference?
When switching provider, you will either request a PAC code or a STAC code. Both are easy to generate, but each one is used for a different purpose.
1. PAC Code (Porting Authorisation Code)
Use this if you want to keep your mobile number. This is the code you’ll give to your new network so they can transfer your number over.
2. STAC Code (Service Termination Authorisation Code)
Use this if you want to cancel your old number completely and start fresh with a new one on the new network.
Since this article is about keeping your number, you’ll be using a PAC code.
How to Get Your PAC Code in Seconds
The easiest method is the UK-wide “Text to Switch” service. This works with every major provider and nearly all MVNOs.
Text to Switch Method
Simply send the word "PAC" to 65075 from the number you want to keep.
You’ll receive a reply containing:
- Your PAC code (three letters + six numbers)
- Any outstanding charges or contract fees
- The validity period (PAC codes expire after 30 days)
This method is free, instant, and avoids speaking to call-centre staff trying to persuade you to stay.
If Text to Switch Doesn’t Work
Rarely, some business accounts or older PAYG profiles may not support automated switching. If that happens, you can request a PAC by:
- Logging in to your network’s app or online account
- Speaking to customer service through live chat
- Calling customer support directly
How to Give Your PAC Code to Your New Provider
Once you have your PAC code, pass it to your new network. Most providers let you submit it through:
- Their mobile app (usually the fastest way)
- The activation page on their website
- A customer-service chat
If your new SIM hasn’t been activated yet, you may need to install it first, make a quick test call, and then submit the code.
How Long Does Number Transfer Take in the UK?
In most cases, the number transfers within one working day, as long as you submit the PAC before 5pm.
The timeline typically looks like this:
- Day 0 (Morning): Submit PAC code to new provider
- Day 1 (Midday or Afternoon): Number switches across
- Day 1–2: Temporary service overlap resolves
Transfers do not usually happen on Sundays or bank holidays. If you submit the PAC late on a Friday, expect completion on Monday.
What Happens During Number Porting?
Short Period of Limited Service
For around 10–30 minutes, you might experience temporary issues:
- Outgoing calls may not connect
- One network may receive your calls while the other sends them
- Mobile data may drop briefly
This is normal. Most UK users barely notice the downtime, but if you rely on your phone for work, plan the switch during non-busy hours.
Your Old SIM Will Stop Working
When the number successfully transfers, your old SIM will lose signal permanently. Replace it with your new SIM (or activate your new eSIM) and your phone number will now live on the new network.
Keeping Your Number When Moving from SIM to eSIM
More UK providers now support eSIM, including major household names and most high-value MVNOs. If you are switching from a physical SIM to eSIM, the process is the same — the PAC code still moves your number.
After the switch completes, your new network will provide either a QR code or an in-app activation process for your eSIM.
Common Problems When Keeping Your Mobile Number
1. PAC Code Has Expired
PAC codes expire after 30 days. If this happens, simply request a new one by texting PAC to 65075 again.
2. Mismatched Details Between Networks
Rarely, some networks may reject the PAC if the account name or type doesn’t match. Contact support for a quick fix if needed.
3. You’re Still in a Minimum Contract
Switching networks doesn’t cancel early-termination fees. Your old provider will text you details about any remaining charges when they send your PAC code.
4. iMessage, FaceTime, or WhatsApp Not Updating
Some apps cache your previous network details. A quick restart or signing out/in normally resolves it.
Tips for a Smooth UK Number Transfer
1. Keep Both SIMs Handy
During the transition, your old SIM may still receive calls for a short while.
2. Restart Your Phone After the Switch
This forces your phone to refresh the network settings and typically resolves most post-port issues instantly.
3. Activate Wi-Fi Calling Immediately
Many UK networks offer Wi-Fi calling, which is especially useful indoors or in rural areas. If you're unsure how to optimise your handset’s connectivity, our connectivity guide offers extra tips.
4. Check Your APN Settings
Some plans need you to refresh your data settings. Most networks send these automatically when your new SIM becomes active.
Why UK Users Switch Networks More Often Now
UK customers are switching providers more frequently than ever due to better SIM-only deals, transparent pricing, and improved coverage across MVNOs. Many networks now compete heavily on data allowances, international call options, EU roaming, and fair prices for PAYG users.
For example, budget networks often run promotions with extra data, while others focus on no-contract rolling plans. If you're switching because your phone feels slow on the new SIM, it’s worth reviewing our performance and system optimisation guide.
After Your Number Has Successfully Moved
Once the porting is complete, your number should work across calls, texts, and apps without issue. If you rely heavily on messaging apps or cloud accounts, double-check that all services recognise your updated network profile.
Some users also notice display settings or carrier menus behaving differently when switching SIMs. If you're personalising your phone again, our guide on display customisation may help.
Final Thoughts
Keeping your UK mobile number when switching provider is quick, free, and hassle-free thanks to the Text-to-Switch system. Whether you're chasing better signal, cheaper data, or improved SIM-only deals, you can move networks in under a day without losing the number you’ve used for years.
As long as you request your PAC code, activate your new SIM, and wait for the short transition window, your number will carry over smoothly. It’s one of the simplest upgrades you can make to your mobile experience in the UK — and it often leads to lower bills, faster data, and better customer service.
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