Dual-SIM smartphones let you use two SIMs 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, however, 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 UK SIM for when you're at home and another that is local to the country you're visiting.

Dual-SIM phones are incredibly popular outside the UK, but for some reason us Brits are being 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, but there are risks involved

Also see: Best Chinese Phones & Best Budget Chinese Phones

Your buying guide to the best dual-SIM phones in 2018

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, 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 at 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 3G or 4G connections, you can use 4G on only one SIM at a time. 

Unlike with calls and texts 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. 

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. 

Another issue when using dual-SIM phones is where your contacts are stored. We found that by default the contacts from both SIM cards are stored in the phonebook.

If you'd rather see the contacts from only one SIM, tap the three dots icon (within the Contacts app) and choose 'Contacts to display'. You can then select All contacts, Gmail contacts, phone contacts or one of your two SIMs.

Best Dual-SIM Phone Reviews

1. Huawei P20 Pro

Huawei P20 Pro
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 9 April 2018

In the P20 Pro Huawei has delivered a stunning phone which should be on your shortlist along with the Galaxy S9 and iPhone X. Sure, there are some niggles such as the lack of stabilisation for 4K video, no headphone jack and no wireless charging,but if your priority is photography then the P20 Pro does not disappoint.

Add in the long battery life, dual SIM slots and great screen and you've got the complete package: this is one of the best phones of 2018.

It's a fair amount more than the regular model so save yourself £200 on the regular P20 if you don't mind 'only' dual rear cameras, no waterproofing and an LCD screen vs OLED.

Read our Huawei P20 Pro review.

2. Xiaomi Mi Mix 2S

Xiaomi Mi Mix 2S
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 16 May 2018

The original full-display smartphone is evolving into something really special. Now with wireless charging, faster performance and a dual-camera that builds in AI, the Mi Mix 2S is a closer rival to western flagships than ever - and at a fraction of the price. 

The Mi Mix 2S majors on performance and design. With its ceramic, mirror-finish case and 18:9 display it looks and feels incredible in the hand.

With full Google services the Xiaomi is easy to recommend, although it's not ideal for selfie and audio fanatics with a poorly positioned front camera and a mono speaker that doesn't make up for the lack of a headphone jack.

Battery life could also be better, and we'd like to see the company finally take the plunge with a Quad-HD display and waterproofing.

Read our Xiaomi Mi Mix 2S review.

3. Xiaomi Mi A1

Xiaomi Mi A1
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 7 November 2017

We're big fans of Xiaomi phones, but have been frustrated by MIUI on many an occasion. The Mi A1 and Mi 5X are to all intents and purposes the same phone, except one runs Android One and the other MIUI 8.5. That's huge news: at last we have a Xiaomi phone we can really get onboard with in the UK and Europe.

The Mi A1 itself is a well-built and decent all-round mid-range Android phone. It's not the fastest phone we've ever seen, and its low-light photography can be faulted. It lacks wireless charging, a futuristic full-screen display, a Quad-HD resolution, waterproofing, even NFC.

But at around £200 it offers amazing value, with good performance, a good camera, a nice design and decent software with timely security updates. If you're on a budget, it's difficult to think of a similarly priced phone that will do a better job.

Read our Xiaomi Mi A1 review.

4. Xiaomi Mi6

Xiaomi Mi6
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 26 May 2017

This really is an amazing phone, and only the Chinese software puts us off recommending it for a UK audience. It is crazy fast, crazy beautiful and crazy priced. If you know your way around Android go and get one, and you won’t be disappointed.

Read our Xiaomi Mi6 review.

5. Honor 9

Honor 9
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 11 December 2017

The Honor 9 is an undeniably impressive phone and although the Honor 10 is out, you can still buy it even cheaper direct from Honor

In performance terms, it's nipping at the heels of the year's top flagships, and only lacking flashy features like waterproofing or a bezel-less screen. It looks great, it runs fast, and it costs less than £300 now.

Read our Honor 9 review.

6. Xiaomi Mi Note 3

Xiaomi Mi Note 3
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 2 May 2018

The Mi Note 3 is a downgrade on the Mi6 and, arguably, the Mi Note 2, but it appeals with a lower price and an attractive premium design. Though it doesn't feature a flagship processor, this is is a very capable smartphone with a very decent dual-camera. Provided you can live without 800MHz 4G and are happy to install Google Play Services yourself, it's difficult not to recommend the Mi Note 3.

Read our Xiaomi Mi Note 3 review.

7. UMIDIGI S2 Pro

UMIDIGI S2 Pro
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 8 May 2018

The S2 Pro from UMIDIGI offers amazing value at just a touch over £200 thanks to its large 18:9 display, huge battery and capacious internal storage. Performance and photography are adequate, making this an excellent budget- to mid-range choice, and worth considering as an alternative to the Moto G6 if you need the extra storage or dual-SIM capability.

Read our UMIDIGI S2 Pro review.

8. Xiaomi Redmi Note 5A (2GB)

Xiaomi Redmi Note 5A (2GB)
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 30 April 2018

The 2GB RAM model we reviewed lacks features compared to the better-specced Redmi Note 5A options that cost only slightly more. There's no fingerprint scanner, a slower processor, a less impressive selfie camera and less memory and storage.

But none of this takes away from the fact this super-budget smartphone offers extraordinary value under £70. It doesn't excel at any one particular thing, but it is capable for less demanding users and nicely designed for a plastic phone.

If you do buy the Note 5A we strongly recommend choosing a Global variant for improved connectivity and the preinstallation of Google Services.

Read our Xiaomi Redmi Note 5A (2GB) review.

9. Nubia Z17 Mini

Nubia Z17 Mini
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 13 April 2018

It's cheaper than the best UK budget phones, yet blows them out the water on performance. For the money the good-looking Nubia Z17 Mini's hardware is more than adequate, it's just a shame it's not running the latest Android software.

Read our Nubia Z17 Mini review.

10. Elephone S8

Elephone S8
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 10 April 2018

The Elephone S8 has a lot to offer under £200, including a large, very decent 16:9 Quad-HD screen, but it's not the upgrade to the Elephone S7 we were hoping for. Its design is a real departure, more Mi Mix Mk II than Elephone S7 Mk II, and it loses nice touches such as the microSD slot and headphone, while upgrading the battery, charging port and cameras. 

Read our Elephone S8 review.