Dual-SIM smartphones let you use two SIM cards in a single phone. Most people who use dual-SIM phones find the functionality useful for mixing work and pleasure, rather than carrying separate phones for their work and personal contracts.
Dual-SIM phones are also useful for maintaining two personal contracts, whereby one might offer a good rate on calls and texts and the other offers unlimited data. Or perhaps you frequently travel abroad and would like to carry a local SIM for when you're at home and another that is local to the country you're visiting.
These days, you don't always need two physical SIMs to achieve this dual-SIM functionality. For example, Google's Pixel 5 supports dual-SIM via eSIM, which means you can have one standard SIM installed in the phone and subscribe to another network via its eSIM. For more on this, see What is an eSIM?
Dual-SIM phones are incredibly popular outside the UK, but for some reason, us Brits have been left out of the dual-SIM party. This is one reason why the Chinese market has become a popular solution for picking up a dual-SIM phone.
Do bear in mind that many smartphones officially sold in the UK are single-SIM variants, whereas alternative models of that very same phone sold elsewhere in the world are dual-SIM. If you have a specific phone in mind, a good place to check is Amazon for any dual-SIM variants of that phone.
Xiaomi Mi 11 - Best Overall
- Fast performance
- Great camera
- Attractive design
- Phenomenal value
- MIUI still sorta sucks
- No IP rating
- No telephoto
The Mi 11 is a fantastic bit of hardware for the price. The fastest chipset around, a beautiful display, and strong cameras are all packaged within a lovely bit of industrial design.
Some will miss the IP rating, though for me the bigger downsides are the choice of a macro over a telephoto lens, the only average battery life, and a software experience that still lags behind the key rivals.
Read our full Xiaomi Mi 11 review
Samsung Galaxy S21 Ultra - Best Camera
- Excellent camera and performance
- Great battery life
- Beautiful display
- No charger may irk some
- Loss of microSD slot
- It's big
After 2020's disappointing Galaxy S20 Ultra, Samsung has finally earned the name with a follow-up that delivers almost everything you could want from an Android flagship - admittedly at a price that only a few can afford, and in a form factor that will simply be too big for some.
The camera is now probably the best in any phone, with a 108Mp main shooter backed up by an ultrawide and two telephoto lenses at different zoom levels.
The expansive 6.8in display delivers both high WQHD+ resolution and adaptive refresh rate up to 120Hz, and with new S-pen stylus support it comfortably fills the productivity niche of the Galaxy Note 20 Ultra too.
Read our full Samsung Galaxy S21 Ultra review
Oppo Find X3 Pro - Best Display
- Best-in-class display
- Excellent battery life
- Phenomenal cameras
- No periscope lens
- Some performance throttling
The Oppo Find X3 Pro is a phenomenal phone by any measure. The 6.7in 10-bit 120Hz QHD+ panel is one of the best displays in any phone right now and Oppo backs it up with 65W wired and 30W wireless charging, a 4500mAh battery, and a top-tier camera that boasts 50Mp sensors on both the main and ultrawide lenses.
You’ll have to live without a periscopic zoom lens - the telephoto here is a measly 2x zoom - but Oppo instead includes a novel microlens camera capable of microscopic super-closeups. That's not the only oddity, as the design itself is utterly unique thanks to a seamlessly sloped camera module built right into the glass of the phone's body.
For pure performance the Find X3 Pro is also hard to beat, with all of the above plus a Snapdragon 888 chip, 512GB storage and 12GB RAM. You just have to be willing to pay the price, as it doesn't come cheap.
Read our full Oppo Find X3 Pro review
Xiaomi Mi 11 Ultra - Fastest Charging
- Incredible specs and display
- Powerful camera
- 67W charging
- Ugly, over-sized camera module
- Big and heavy
- MIUI not for everyone
The Mi 11 Ultra packs some of the absolute best hardware out there, from top internal specs to a powerful camera, beautiful display, and fast charging using both wired and wireless methods.
There are down sides though. The sheer price is an obvious one, as is the fact there is no promise of software updates, but honestly the design is a bigger flaw. The Mi 11 Ultra is not only big, but thanks to the ungainly camera module it is also simply quite ugly.
Read our full Xiaomi Mi 11 Ultra review
Samsung Galaxy S21 - Best For Ease Of Use
- Improved battery life
- Superb performance
- Decent software
- Nice design
- Cameras are relatively unchanged
- Some downgrades from S20
- No charger
On the surface, Samsung has brought better specs - including 5G as standard and the latest Snapdragon 888/Exynos 2100 chip - to the table for less than the asking price of the 4G-only build of the Galaxy S20.
In actuality, it's prioritised those upgrades to ensure the S21 appears as relevant and current as possible, without going out of its way to really set the bar for forthcoming 2021 rivals.
The Galaxy S line's unofficial position as the 'default alternative' to those who don't want an iPhone isn't likely to change with everything the Galaxy S21 has to offer, and for most users, this is still as much of a well-rounded, capable and reliable device as the S20, S10 and beyond have been.
If you're looking for Samsung to push the flagship phone envelope, however, the Galaxy S21 isn't the phone to do it.
Read our full Samsung Galaxy S21 review
OnePlus Nord 2 - Best Mid-range Phone
- Excellent software
- Great design
- Strong all-rounder
- Only 90Hz display
- Slightly thick
An outstanding follow-up to 2020's best mid-range phone, with great performance, 5G, OnePlus's signature Oxygen OS user experience, and a near-flagship main camera. What's not to love?
What the OnePlus Nord 2 really demonstrates is the company's ability to prioritise the features that users are looking for right now and wrapping them up in an attractive package with a compelling price point.
The Nord 2 misses out on flagship niceties like wireless charging and waterproofing, but those are really the only compromises made here.
Read our full OnePlus Nord 2 review
OnePlus 8 Pro - Feature-packed
- Finally adds waterproofing
- 30W wireless charging
- Excellent camera
- No telephoto camera
- large build
The OnePlus 8 Pro is arguably the company's first full flagship, finally incorporating long-requested features like wireless charging and an IP68 waterproof rating to make it a genuine contender with Samsung's top flagships.
Understandably, the price initially went up accordingly, but it still represents serious value by flagship standards, and you will save at least some money by opting for OnePlus over most other manufacturers. (Since the release of its successor, its price has thankfully dropped).
The 8 Pro camera is OnePlus' best yet, and while it still lags behind rivals slightly in software the hardware is among the best around, which has helped to close the gap considerably. Throw in 5G, a great design, and the best Android skin around and the OnePlus 8 Pro is easy to recommend to anyone who can afford it.
Read our full OnePlus 8 Pro review
ZTE Axon 30 Ultra - Best Value Flagship
- Incredible camera
- Stunning screen
- Svelte design
- Great value
- No wireless charging
- No microSD slot
The ZTE Axon 30 Ultra is a stunning proposition and offers buckets of value. It’s a genuinely exciting flagship smartphone in practically every department: it’s lightweight, feels great in the hand, the 144Hz 6.67in AMOLED display is detailed and crisp, the Snapdragon 888 allows it to perform like a gaming phone and, well, that camera setup is incredible.
Comprised of three 64Mp snappers and a 5x telescope lens, the Axon 30 Ultra’s rear camera offering is versatile, and unlike some, images captured across all sensors are comparable in terms of quality, detail and colour balance.
There are plenty of creative shooting modes available to make the most of the system, and it caters to videographers with [email protected] video recording too.
The results are comparable to those taken on ultra-premium smartphones like the Galaxy S21 Ultra and iPhone 12 Pro, but with one key difference – it’s hundreds of pounds/dollars cheaper.
The software could do with a visual tweak here and there and there's no wireless charging, but those are minor complaints in what is an otherwise phenomenal 2021 flagship.
Read our full ZTE Axon 30 Ultra review
Xiaomi Poco X3 Pro - Best Performance on a Budget
- Phenomenal performance
- Big 120Hz display
- Long-lasting battery
- Big and bulky
- No 5G
- Average camera
The Poco X3 Pro is a phone designed for Android gamers or power users on a budget, though it might also appeal to those who want to go big on specs in order to futureproof their phone.
If pure performance isn’t your priority, then you can find phones that are slimmer and lighter, with better camera performance, for around the same price.
What you won’t find is any phone that can match this pound for pound right now. This is near-flagship processing power in one of the cheapest phones on the market, and it’s almost ludicrous that Xiaomi has pulled it off.
Read our full Xiaomi Poco X3 Pro review
Xiaomi Redmi Note 10 Pro - Best Budget Option
- Stunning 120Hz AMOLED display
- Long battery life
- Excellent cameras
- No 5G
- No OIS
- Huge camera bump
- MIUI not for everyone
The Redmi Note 10 Pro is essentially an upgraded Poco X3 NFC with a nicer display and better camera.
The 6.67in 120Hz panel boasts AMOLED tech, meaning superb contrast and vibrant colours. The 108Mp lead camera, meanwhile, excels and comes accompanied by a pair of secondary snappers that exceed expectation.
Fun extras like 33W fast charging, a headphone jack and even an IR blaster elevate the Redmi Note 10 Pro from good to great budget offering, considering what Xiaomi's incorporated here.
Read our full Xiaomi Redmi Note 10 Pro review
Xiaomi Mi 11 Lite 5G - Thinnest 5G Phone
- Respectable peformance
- Impressively thin and light
- MIUI can be unintuitive
- Better value elsewhere
- No water resistance
While the standard 4G-only Mi 11 Lite is already an impressive feat of engineering, thanks to its slim profile, the fact that this 5G equivalent isn't really any thicker, larger or heavier, despite delivering even more power, is an impressive achievement in and of itself. It packs in more than just faster cellular connectivity, too, with a superior chipset and a few other extras that collectively render it a more powerful and competitive mid-range entry.
Mi 11 Lite 5G offers up a pleasingly well-rounded experience and heaps of performance for the price. However, it does occupy a crowded mid-range space, where devices are vying for interest based on standout features, without demanding flagship prices.
As such, if you're looking for the thinnest phone worth buying right now, this is it. If that waistline isn't one of the biggest driving forces behind your purchasing decision, though, there are a number of competitors for around the same money that will also fit the bill.
Read our full Xiaomi Mi 11 Lite 5G review
OnePlus 8T - Recommended
- 120Hz display
- 65W fast charging
- Android 11
- Aging camera
- OnePlus Nord is better value
Ignore the price and the OnePlus 8T doesn’t feel like a desperately exciting upgrade from the 8 in some respects. But once you realise the price has dropped the phone begins to look much more compelling.
120Hz and 65W charging are welcome upgrades, even if they’re the sort of techie features that most users likely won’t care about too much. The software changes brought about by Android 11 are also almost all welcome, not least the always-on display.
From a hardware perspective the camera is the only real stumbling block, made worse by the decision to include the same main lens in the OnePlus Nord. And that’s really the main challenge facing the 8T: it’s good, but pound-for-pound the Nord is still better, leaving OnePlus hoist by its own petard.
Read our full OnePlus 8T review
Sony Xperia 1 III - Recommended
- Superb performance
- Best-in-class audio
- Gorgeous display
- Underwhelming longevity
- Slightly dim display
- Prone to heat
If the Xperia line proves anything, it's that Sony enjoys walking its own path; something that's perfectly reflected in the sheer amount of world firsts that the Xperia 1 III brings to the table.
Existing Sony fans will have no trouble finding value in the 1 III's unique feature set (unless they own last year's 1 II, as this feels like a more incremental upgrade in that regard). But, for everyone else, it's a matter of weighing up whether those USPs trump the small missteps Sony has made with some of this phone's fundamentals.
Not only do rivals like Apple's and Samsung's top-tier alternatives come with better selfie cameras, brighter displays and longer-lasting batteries, but they offer greater peace of mind. The promise of long-term software support and tighter integration with their respective product ecosystems is something Sony knows it can't compete on and so doesn't try to with the 1 III.
Read our full Sony Xperia 1 III review
Your buying guide to the best dual-SIM phones in 2021
How do dual-SIM phones work?
Something we've noticed when shopping for dual-SIM phones is that the manufacturer very rarely provides any information about the functionality other than it exists. It doesn't tell you how the dual-SIM functionality works in practice, nor whether both SIMs support 4G/5G, or even what size SIM cards they accept.
You can never assume; you'll need to contact the manufacturer or check spec tables, reviews or forums to find out this information.
In all the dual-SIM phones we've tested, both SIMs are on standby at all times (known as dual-standby phones), but you can actively use only one SIM at a time. This means that either SIM can accept a phone call or text at any time, without you having to actively swap between them or reboot the phone.
However, if you get a call on one number while a call is active on the other, it won't start ringing in your ear or give you the option to put the first caller on hold - the call will simply not be successful.
What is the difference between Dual-Standby and Dual-Active?
Dual-active SIM phones use two modems and allow you to receive calls on both numbers at once.
If it's you who wants to make a call or send a text, Android has a standard SIM Management menu that lets you specify which SIM should be used for voice calls, video calls, messages and mobile data. You can either specify a particular SIM for each of these tasks, or leave the setting as 'Always Ask'.
The data connection is where there seems to be a lot of confusion when it comes to dual-SIM phones. Whereas both SIM slots on some dual-SIM phones are capable of supporting 4G or 5G connections, you can use data connectivity on only one SIM at a time.
Unlike with calls and texts, typically speaking the data connection can't be on standby for both SIMs; you must specify which SIM you want to use rather than select one when prompted - though some phones will let you set them to switch to the other SIM when the first can't make a connection.
By default, when you are using the data connection on one SIM and a phone call comes in to the other, it will pause the data connection on the first.