ukdeals If you already own a decent phone, paying for a new handset every month is money down the drain. That’s where SIM-only deals come in — you get the minutes, texts and data you need, without financing a phone you don’t want. In this guide, we’ve rounded up the best SIM-only deals UK shoppers can get right now, broken down by budget, data allowance and network, so you can find the right plan in minutes.
Table of Contents
What Is a SIM-Only Deal?
A SIM-only deal is a mobile contract that includes calls, texts and data but doesn’t come bundled with a handset. You simply receive a SIM card (or an eSIM sent digitally) and pop it into a phone you already own. Because the network isn’t subsidising a new phone, SIM-only plans are usually far cheaper than a standard pay-monthly contract with a handset attached.
Since Ofcom’s 2021 ruling banned network-locked handsets sold in the UK, almost any modern phone can accept a SIM from any provider, making it easier than ever to switch and save.
Two main contract types to know:
- Rolling (30-day) SIM-only deals — cancel any time with 30 days’ notice, ideal if you want flexibility.
- 12–24 month SIM-only contracts — usually cheaper per month in exchange for a longer commitment.
Best SIM-Only Deals UK: Quick Comparison
| Plan Type | Typical Monthly Price | Best For |
|---|---|---|
| Budget (1–5GB) | From around £5–£8/month | Light users, second phones |
| Mid-range (20–100GB) | Around £10–£15/month | Everyday streaming & social media |
| Unlimited data | Around £16–£25/month | Heavy streamers, hotspot users |
| Family/multi-SIM | Varies — often 10–20% off per extra SIM | Households with 2+ phones |
Prices are indicative and change frequently — always check the live price on the provider’s site before buying.
Best Cheap SIM-Only Deals (Under £10/Month)
If you’re a light user who mostly relies on WiFi, a budget MVNO (Mobile Virtual Network Operator) plan is the smartest way to cut your bill. Providers like Smarty, Lebara, Voxi, giffgaff and Asda Mobile run on the same underlying networks as the big four (EE, O2, Three, Vodafone), so coverage is nearly identical — you’re just paying less because these brands have lower overheads and no shops to run.
Look out for:
- No mid-contract price hikes (some MVNOs guarantee fixed pricing for the full term)
- Data rollover, so unused GB carries into next month
- EU roaming included at no extra cost
Best Unlimited Data SIM-Only Deals
For streamers, gamers, or anyone using their phone as a personal hotspot, an unlimited data SIM removes the anxiety of running out mid-month. The big four networks (EE, O2, Three, Vodafone) tend to lead here because unlimited plans rely on strong core network capacity — Three in particular has invested heavily in 5G coverage, often making it one of the most competitively priced unlimited options.
Before choosing unlimited, check for:
- Fair usage/throttling policies — some “unlimited” plans slow speeds after a very high threshold
- 5G availability in your postcode — no point paying for 5G-ready if your area is still 4G-only
- Tethering/hotspot allowances, which aren’t always unlimited even on an “unlimited data” plan
- Mobile network signal where you live to ensure better coverage and full strength
Best SIM-Only Deals UK for Families
If more than one person in your household needs a SIM, multi-SIM discounts can meaningfully cut the total bill. Sky Mobile, BT Mobile (which discounts SIM-only plans for existing broadband customers), and Vodafone’s family add-ons are worth comparing, since data can often be shared or pooled across SIMs rather than each person buying a separate large allowance.
Which Network Is Best for SIM-Only Deals?
| Network | Runs On | Known For |
|---|---|---|
| EE | Own network | Widest 4G/5G coverage in the UK |
| O2 | Own network | Perks via O2 Priority, strong customer service |
| Three | Own network | Competitive unlimited data pricing, fast 5G |
| Vodafone | Own network | Strong international roaming |
| giffgaff | O2 network | Flexible, no-contract “goodybags” |
| Smarty | Three network | Simple, cheap, data rollover |
| VOXI | Vodafone network | Social media apps that don’t use data allowance |
| Sky Mobile | O2 network | Data rollover (“Piggybank”) for existing Sky customers |
| Tesco Mobile | O2 network | Clubcard points on your bill |
MVNOs are a great choice if your priority is price, since you get near-identical coverage to the parent network for less. The big four are worth the extra cost if you want direct customer support, exclusive perks, or the newest network features first.
How to Switch to a SIM-Only Deal
- Check your current contract end date to avoid early termination fees.
- Get your PAC code (Porting Authorisation Code) if you want to keep your number — text PAC to 65075.
- Or get a STAC code if you’re leaving without keeping your number — text STAC to 75075.
- Choose your new SIM-only deal and give the provider your PAC code to complete the switch.
- Your old contract ends automatically once the new SIM is activated — no need to cancel separately.
For full consumer rights around switching, Ofcom has an official guide on mobile switching rules.
FAQs
Is SIM-only cheaper than a phone contract?
Yes. Because you’re not financing a handset, SIM-only deals are typically 50–70% cheaper per month than an equivalent pay-monthly phone contract.
Can I use any SIM in any phone?
n most cases, yes. UK law has required unlocked handsets since December 2021, so nearly all phones sold since then work with any network’s SIM.
What happens to unused data on a SIM-only plan?
It depends on the provider. Some networks (like Smarty and Sky) let unused data roll over to the next month; others reset your allowance every billing cycle.
Do SIM-only deals include 5G?
Most modern SIM-only plans support 5G at no extra cost, but you’ll need a 5G-compatible phone and to live in a covered area to actually use it.
How do I cancel a rolling SIM-only contract?
Rolling (30-day) SIM-only deals can usually be cancelled any time by giving 30 days’ notice through your online account or by contacting customer support.
