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Three's unlimited data SIM:
6 months half price at £11 a month

Three phone and SIM card

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You can now get Three's unlimited data SIM only plan half price for 6 months. We look at how the offer works and any restrictions on the data. SIM Sherpa is your trusty guide. Last updated: March 11th 2020.

What's the deal?

Unlimited everything, half price for six months  (4.5/5)

Three SIM card

It's unlimited data. And it's priced at £11 a month for your first 6 months, then £22 a month. That averages out to £19.25 a month over the course of the 24‑month contract.

You also get Three's usual benefits of 99% 4G population coverage, inclusive roaming and perks like free easyJet upgrades and it comes with 5G data speeds at no extra cost too.

Useful link: Read full benefits below

5G data
£11 a month
for 6 months, then £22 a month
on a 24-month contract
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What's good about it?

It's genuinely unlimited data - and that's pretty rare

Three offer banner

On a 24-month contractSee full offer

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If you've ever put your phone down because you're worried about going over you data usage limits, Three's unlimited data SIM puts an end to that. You're free to use as much as you like in the UK at no extra cost.

And you're not limited by any sneaky traffic management or throttling rules when you use it in this country either. Others sometimes promise no data caps but then slow you down to stop you using too much.

You can also use it for tethering (personal hotspot), which is where you connect tablets or laptops to your phone so they can access internet anywhere you have mobile signal. That's unlimited in the UK too.

The only restrictions come when you're using your SIM abroad. There, you won't be able to use tethering, a monthly cap of up to 19GB applies (depending where you are) and Three reserve the right to slow down your connection while roaming.

If you managed to use 1000GB in a month, Three say this might trigger them looking into whether you're definitely using the SIM for just personal use (you can't use the SIM for commercial purposes).

That doesn't mean you can't use that much. And it's not an actual fixed limit. It's just the point at which Three might look into your usage.

Useful link: Read Three's terms and conditions

Three's network offers good coverage and speeds

Three's network map

Make sure you'll be able to use unlimited dataCheck Three's coverage

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It's true that Three aren't the UK's largest network but their 4G now reaches 99% of the population in the places where they live. There is still work to do in rural locations. The deal gets you 5G for no extra cost too.

We'd always recommend checking any network's coverage before you sign up. Use Three's official network map here to do so. Be sure to look not just at home but anywhere you'll be using your phone.

Over 4G, we'd expect Three customers to get download speeds of around 20 Mbps on average, which currently puts them just behind Vodafone and a way off EE.

This is a healthy score that is similar to what many will be getting home over non-fibre broadband. It'll support smooth video and audio streaming and let you browse the general internet.

Customers in these 66 locations also have access to 5G data speeds. Three say it's the UK's fastest 5G network with 140MHz of spectrum, so you can download a high‑res film in seconds.

Useful link: Check Three signal in your area

The £19.25 average cost beats Three's competition

Vodafone's unlimited data plan banner

We do rate Vodafone's Unlimited Max planSee the plan

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Over the 24-month contract, £11 a month for 6 months plus £22 for 18 months works out to £19.25 on average (this will creep up when you're paying £22 if you don't re-compare once out of contract though).

That currently undercuts all other mobile networks with unlimited data plans:

The average price over 24 months can be beaten

Three's Black Friday offer banner

There's a hidden flat £18 deal tooSee hidden offer

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We closely monitor Three's pricing on their unlimited data deal. They usually have an offer of sorts running on the plan, including this hidden flat £18 deal:

This plan is worth taking instead of the 6-month half price offer, as it's cheaper and has a much shorter commitment.

Paying £18 a month works out more expensive in the beginning, but works out cheaper the longer you're on Three, because you're not paying £22 in the later months.

Otherwise, the plan has previously been priced as little as £20-flat or as much as £32.

Useful link: See Three's SIM only deals page

SIM Sherpa can help you find your next SIM only deal

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