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 Phones 2018

1. Xiaomi Mi 8 Pro

Xiaomi Mi 8 Pro
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 9 November 2018

At £499 the Mi 8 Pro is an incredible buy, undercutting every rival flagship phone in the UK - and now that Xiaomi phones are easily available in the UK, there's no reason not to consider it.

With powerful performance, decent cameras, some genuinely useful software, a fancy in-display fingerprint sensor and a cool transparent back cover, this is a great all-rounder at a fantastic price.

Read our Xiaomi Mi 8 Pro review.

2. OnePlus 6T

OnePlus 6T
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 29 October 2018

This is one of the best phones you can buy even if it is the first OnePlus phone without a headphone jack. An in-screen fingerprint sensor, better speaker and more battery is the pay-off, and it's worth it.

The large display is excellent, the dual cameras are more capable than ever and performance is the best you can get on Android right now along with the Pixel 3.

You'll need to like the colour black, but OnePlus continues - just - to undercut industry prices enough to stand out.

Read our OnePlus 6T review.

3. Vivo Nex

Vivo Nex
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 23 August 2018

It's not perfect, but the Vivo Nex is certainly an impressive smartphone that offers something a little different for consumers. It boasts a fingerprint scanner embedded in the display, a notch-less design and a front-facing camera that pops out of the frame when required. It's not just a gimmicky concept phone though; the performance is good enough to compete with flagship smartphones from the likes of Samsung, OnePlus and LG. 

Oh, and it's £100s cheaper than the iPhone X and Samsung Galaxy S9+ too. 

Read our Vivo Nex review.

4. Xiaomi Mi8

Xiaomi Mi8
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 5 October 2018

Astonishing value, insane performance, awesome photography, a larger than ever 18.7:9 AMOLED display and a cool new 3D Face recognition feature are all reasons why you should rush out and buy the Mi 8. Right now it costs just £438.33/US$569.99/€490.20 from GearBest, which is several hundred pounds cheaper than many of the phones with which it competes.

We're sad to see Xiaomi not keeping up with its rivals in terms of wireless charging, waterproofing and a Quad-HD screen, and that the highly anticipated in-display fingerprint is unique to the Explorer Edition, but at this price we can hardly complain. Amazing phone, highly recommended.

Read our Xiaomi Mi8 review.

5. Huawei P20 Pro

Huawei P20 Pro
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 20 June 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.

6. Honor 10

Honor 10
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 15 November 2018

Continuing its run of good form, the Honor 10 is the best mid-range phone you can buy right now.

Battery life might not be anything to write home about but that's not unusual and there's so much to like here. Much of what the Honor 10 offers, like display, cameras and build quality are at the level you'd expect from a phone twice the price.

The software is better than ever and you get a whopping 128GB of storage as standard. Add in smooth performance, a headphone jack, dual-SIM and attractive design and you can see why this is the current mid-range king.

Read our Honor 10 review.

7. 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.

8. Xiaomi Mi A2

Xiaomi Mi A2
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 9 November 2018

The inclusion of Android One makes Xiaomi phones so much more easily accessible to UK- and US users - and that's a very good thing, finally allowing those outside China and India (and more recently Spain, France and Italy) a taste of what else is out there on the market. The Mi A2 (also available running MIUI as the Mi 6X) merely whets our appetite for what's coming our way when Xiaomi officially launches in the UK on 8 November.

A fantastic budget phone, the Mi A2 is just £199 and easily obtainable from Amazon. It combines decent build quality with a nice display, good all-round performance and a well-specced trio of cameras. It out-specs and out-performs every other phone in our budget smartphone chart.

Read our Xiaomi Mi A2 review.

9. 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.

10. 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.

11. 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.

12. Xiaomi Redmi 6 Pro / Mi A2 Lite

Xiaomi Redmi 6 Pro / Mi A2 Lite
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 5 October 2018

Xiaomi's Redmi 6 Pro and Mi A2 Lite are one and the same, with the former running MIUI 9 and the latter Android One with full 4G LTE support in the UK. Which you buy really depends on where in the world you are and whether you need Google services preinstalled.

GearVita supplied our Redmi 6 Pro review sample. Right now you can pick up the $219.99 (£171.53) Redmi 6 Pro with $30 off (valid until 31 August 2018 with coupon code RMI6PRO). Shipping is not free, but not extravagant either.

GearBest supplied our Mi A2 Lite, and offers the Android One phone at £170.96/$215.99 with free delivery to the UK.

There's a 19:9 Full-HD+ panel with notch display, a dual-camera at the rear and genuinely usable performance. With 64GB of storage and the ability to add a microSD card up to 256GB without sacrificing dual-SIM support, the Redmi 6 Pro or Mi A2 Lite is an excellent budget buy.

Read our Xiaomi Redmi 6 Pro / Mi A2 Lite review.