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Three SIM Only Review

Three ( 3 ) SIM Only Review




+ Unlimited data

- Less 4G coverage than some other operators

+ Low prices

- Extras only available on Advanced plans

+ Short-term plans



"Three SIM Only is great value, with a wide range of plans, handy extras and high data limits. If 4G coverage was better this would be the perfect SIM Only service, but it's still close."

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8GB data

Unlimited minutes

Unlimited texts

£10 a month

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12GB data

Unlimited minutes

Unlimited texts

£15 a month

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Unlimited data

Unlimited minutes

Unlimited texts

£22 a month

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Full Review

Signing up to a mobile network doesn’t have to mean getting a new phone. If you’re happy with your current one or just want to buy a new handset outright you can also go SIM Only, potentially saving yourself some money in the process.

But deciding to go SIM Only is only the first step, you’ve then got to consider which network to join, as they all have their own strengths and weaknesses.

Here we’ll look at Three SIM Only, analysing what makes it good, how it could improve, and how it compares to SIM Only on other networks.


Three offers a range of SIM Only plans, with data limits of between 500MB and unlimited, while you can also get between 200 and unlimited minutes, and all plans come with unlimited texts.

However, that full range is only available on Advanced Plans, which include a number of extras (detailed below). Opt for a cheaper Essential Plan and you can’t get more than 8GB of data.

That same range of allowances is available on both 12-month and 30-day plans, so you have a lot of choice and – if you choose a 30-day plan – a lot of flexibility.

The downside to the 30-day ones is that they cost more per month than being locked in for 12 months does.

As an example, the very cheapest SIM Only plan right now is a 12-month Essential Plan with 500MB of data and 200 minutes. That costs just £6 per month.

Get those same allowances on a 12-month Advanced Plan and you’ll pay £7 per month, while if you choose those allowances on a 1-month Essential Plan it shoots up to £10 per month, and on a 1-month Advanced Plan it costs £12 per month.

So you have a huge number of options, allowing you to perfectly balance plan length, allowances, extras and price. This can make picking the right plan seem complicated, but on the whole we think choice is a good thing, and you get more here than on most networks.

It’s also worth noting that Three is the only network to offer unlimited data SIM Only plans, other than Giffgaff, which severely limits your speed once you exceed 6GB, so if you’re a heavy data user that’s a huge point in its favour.

Performance and extras

So we’ve established that Three has a wide selection of plans. Enough, in fact, to suit almost anyone. But a SIM Only plan is only as good as the network it’s on, so how does Three fare?

Perhaps the main consideration is coverage, for which Three does reasonably well but with room for improvement. It has 97% 3G population coverage, so chances are you’ll at least be able to get a 3G signal wherever you are.

4G isn’t quite so good, at over 65% (exact up to date figures are hard to come by), but it’s improving all the time and helped by things like Wi-Fi Calling and 4G Super-Voice. It’s also the most recommended network based on a recent YouGov survey.

And you can get a lot of extras on Three’s SIM Only plans. Opt for an Advanced Plan, which means paying slightly more than for an Essential one, and you get access to Feel At Home, which lets you use your allowances abroad in 60 destinations at no extra cost. That’s great for anyone who travels or even takes the occasional holiday abroad.

And Advanced Plans also let you tether, so you can use your phone’s internet connection to get other devices online. They’re handy bonuses that we’d recommend paying the extra for, but it’s great that they’re also optional. If you have no interest in them and would rather save a bit of money instead, that’s possible.

You’ll also benefit from a trio SIM when you opt for Three SIM only. These contain SIM cards of all three sizes (standard, micro and nano), so you can just pop out the one that’s the right size for your phone, rather than having to request a specific size or find an adaptor.

Comparison to SIM Only on other networks

So it’s fair to say that Three offers a good SIM Only service, but how does it compare to rivals? The table below will give you an overview.

UK Networks SIM Only deals


Max Data / Contract Length

Starting Price



Unlimited / 1 or 12 months


Feel At Home, unlimited data


60GB / 12 months


High speeds, strong 4G coverage


80GB / 12 months


Inclusive entertainment


50GB / 1, 12 or 18 months


O2 Priority, free access to Wi-Fi hotspots

BT Mobile

40GB / 12 months


High speeds, strong 4G coverage


4GB / 1 month


Basic plan is free


Unlimited / 1 month


Unlimited data - speed throttle over 6GB

Plusnet Mobile

4GB / 1 month


Strong 4G coverage

Sky Mobile

25GB / 12 months


Data rollover

Tesco Mobile

50GB / 1 or 12 months


Wide selection of plans

Asda Mobile

15GB / 1 month


All plans are 30 day

iD Mobile

40GB / 1 month


Data rollover


15GB / 7 or 30 days


Inclusive international calls

Virgin Mobile

50GB / 12 months


Data rollover

As you can see, Three is cheaper than any other major UK network, and competitive with most of the MVNOs (Mobile Virtual Network Operators) too. It’s also one of only two networks to offer unlimited data, and, as mentioned above, it’s better for this than Giffgaff, as Giffgaff throttles your speeds above 6GB.

Add in a selection of both 1 and 12 month plans, where some networks only have one or the other, and Three is clearly ahead of most.

Although all networks now offer some amount of free roaming, as they’re required to in the EU, Three goes above and beyond with Feel At Home, letting you roam in many places outside Europe too.

Really, the only area where Three doesn’t win out is 4G coverage, so you might be limited to 3G speeds in more places than some rival networks.

But even then, it’s only really EE and networks which run on EE’s infrastructure (namely BT, Plusnet and The People’s Operator) that have a big advantage, and they’re let down in other ways, with high prices and only 12 month plans in BT and EE’s case, and low data limits in Plusnet and The People’s Operator’s.


Although Three’s 4G coverage holds it back a bit, that’s improving all the time and in almost every other way it has a formidable SIM Only offering, with a wide range of plans, including some with short contract lengths, and some with unlimited data.

Its roaming service is better than rivals and it has good value plans including - at the low end - cheaper prices than any other major UK network. If you can live without comprehensive 4G coverage, Three is probably the SIM Only network to go for.

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