The SIM port dance — never pay the post-intro price again.
Cheap SIM deals lure you in with a low intro price, then jump to a much higher "standard" rate after a few months. The fix: port your number out to a free SIM for a day, then port back as a "new customer" and re-trigger the cheap price. Same number, done in ~2 days, for £0.
The port dance, in one picture
Your number leaves your current network, parks on a free SIM for a day, then returns on a fresh new-customer deal. You keep the same number throughout.
What is the SIM port dance?
The SIM port dance (sometimes called the "Lebara port dance" or just "porting out and back") is a simple way to keep paying cheap new-customer prices on a SIM-only plan instead of rolling onto the much higher standard rate when your introductory offer ends.
Budget networks like Lebara, Smarty, Lyca, iD Mobile and Voxi advertise headline deals — often £1–£2 a month for 6–9 months — that quietly jump to £5–£8+ once the intro period is up. Because those prices are reserved for new customers, you can re-qualify simply by signing up again on a fresh SIM. The only catch is that you want to keep your existing phone number, and you can't port a number onto the same network it's already on. So you "dance" it through a free third network for a day, then bring it back.
It relies entirely on Ofcom's free text-to-switch (PAC) system, which every UK network must support — so it's a legitimate use of your consumer right to keep your number, not a loophole or a hack. Start to finish it takes about two days and costs nothing (or £1 if you use a 1p Mobile SIM as the mule).
If you like this kind of low-effort saving, it pairs well with our bank switching playbook and the full free-money roadmap.
How this actually works
Keeping your number is a right
Ofcom's free "text-to-switch" PAC system carries your number to any UK network. The dance just uses it twice — out, then back.
A new SIM = a new customer
Intro prices are for new customers. Sign up on a fresh SIM and you qualify again — the port just brings your old number along for the ride.
The mule is just a parking spot
You can't port a number to the same network it's on, so it parks on a free third network for ~1 day, then comes home.
The temporary "mule" SIM
This is the network your number sits on for about a day in between. It is not a contract and costs nothing (or £1). Just don't use the same network you're porting back to.
Three PAYG
- Free SIM, no contract, no top-up needed
- eSIM available — instant, skips the postal wait
- Reliable porting, well-trodden by the community
- Now runs an ID / card-address check (but takes no payment)
- Can only receive calls/texts on the temp number until you port back
1p Mobile
- £1 SIM but comes with £10 of credit (so not really a cost)
- Simple activation, no credit check
- Can stay on it up to 120 days if you change your mind
- £1 upfront
- Posted SIM — order early
Any cheap PAYG
- Smarty, Lyca, Giffgaff etc. all work as a mule
- Pick whichever delivers an eSIM fastest
- Avoid using the SAME network you're porting back to
- Some charge ~£1 or need a small top-up to activate
Shortcut: use eSIMs
Both your mule and your target network almost certainly offer eSIMs. If your phone supports eSIM, take that option on both — it's instant (a QR code, no post), which removes the only real delay in the whole dance.
Port out Monday → back by Wednesday
Six steps. The only number you ever text is 65075 (the UK text-to-switch line). Take it slow on switch days and your number moves cleanly the whole way.
- 1Setup
Order your two SIMs (use eSIM if you can)
Order a free port-mule SIM (Three is the easy pick) AND a brand-new SIM on the network/deal you want to land on. The new SIM is what makes you a 'new customer' again. Posted SIMs take a few days — eSIMs are instant, so use eSIM on both if your phone supports it.
- Order both before you start — they don't activate until you put them in a phone
- eSIM = no postal wait; physical SIM = allow ~1 week to arrive
- Don't activate the new target SIM yet
- 2Setup
Request your PAC code
Text PAC to 65075 from your current number. This is the UK-wide 'text-to-switch' service — every network must give you a PAC this way, free, within a minute. The code keeps your number and is valid for 30 days.
- PAC = Porting Authorisation Code (keeps your number)
- Works on every UK network by law since 2019
- You'll get the code by text almost instantly
- 3Port out
Port your number OUT to the mule
Activate the mule SIM, then give its provider your PAC to start the switch. Schedule it for a weekday — ideally a Monday — and avoid weekends, which can cause porting issues. You can usually book the port date a few days ahead.
- Activate the mule SIM (pop it in a phone / scan the eSIM QR)
- Submit the switch form with your PAC
- Pick a weekday port date; avoid Fri–Sun
- 4Port out
Switch day — don't touch anything
On the day the port runs, do NOT request a new PAC — that can break the port. Just confirm the switch completed: test that calls and texts reach your number on the mule SIM. It can take until late evening to go through.
- No PAC requests on switch day
- Confirm calls + texts arrive on the mule
- Your old plan ends automatically when the number leaves it
- 5Port back
Next day — get a fresh PAC from the mule
Once the port has completed, request a new PAC from the mule network (Three: text PAC and your date of birth to 65075). This is the code you'll hand to your target network to bring your number back.
- Wait until the port is fully done (usually next day)
- Three format: text 'PAC DDMMYYYY' to 65075
- Free — no top-up needed
- 6Port back
Activate the new SIM + port your number back
Activate your new target SIM (the cheap new-customer deal), then start the port back using its PAC. Do it before midday to switch the next working day. Your number lands back on the new plan — same number, fresh intro price.
- Activate the new SIM and link it to your account
- Start the port-in with the mule's PAC, before midday
- Number returns next working day on the new intro deal
Example: the Lebara dance
Lebara is the classic case. Its cheap intro deals (often around £1–£2/month for 6–9 months) revert to a much higher standard price afterwards. Here's the dance in real terms.
The problem
Your cheap intro rate ends and the plan jumps to the standard monthly price — sometimes 4–5× what you were paying.
The dance
Order a new Lebara SIM on a fresh intro deal + a free Three SIM. Port out to Three, then back to Lebara on the new deal — another 6–9 months at the cheap price, same number.
Prices change weekly. The specific intro deals rotate constantly and the cheapest one today may be gone next week. Don't chase a number — set a deal alert, then grab whatever the best live intro deal is when you're ready to port. Lebara also tends to surface these via MoneySavingExpert and HotUKDeals promo links.
Timing & gotchas
The dance is simple, but a handful of details are worth getting right.
Start before your price jumps
If your rate rises on a set date, have both SIMs ready and start the dance about a week before, so you're back on the new deal before the higher price ever bills.
Port near the end of your billing cycle
Most networks don't refund the unused part of a month when your number leaves. Time the port-out for late in your current cycle to avoid binning days you've paid for.
Never request a PAC on a switch day
Requesting a new PAC while a port is mid-flight can break it. Wait until the port has fully completed (test calls and texts) before the next step.
Keep a spare SIM handy
While your number sits on the mule for ~1 day you may be able to receive but not make calls/texts. A cheap spare SIM covers you for that window.
Frequently asked
Frequently Asked Questions
Related guides
Never overpay for a SIM again
Set a deal alert so you know when a fresh cheap intro deal lands — then do the dance and lock in another cheap run.