Dual SIM Phones

Picture of a dual SIM phone

Dual SIM phones allow you to operate two SIM cards in the same phone simultaneously (no pun intended). There’s a huge range of features that often come with them; one of the most practical examples for dual SIM phones is the ability to have a personal and work SIM card, both operational in the same device.

Well established in most parts of Asia, Dual SIM phones have taken a little while to catch on in the UK. However, since 2010, with the rise of the smartphone, dual SIM is becoming more integrated globally.

What does Dual SIM mean?

Dual SIM simply refers to the capacity to operate two separate sims at once in a single device, typically a smartphone. Manufacturers have seamlessly developed and integrated this feature into new smartphones, tablets, and now smartwatches. Users can use any kind of SIM card with these devices - the most common sim types these days are the Micro SIM, Nano SIM card, and the eSIM.


How do Dual SIM phones work?

Dual SIM phones work by switching network provisioning functionality from one SIM to another, which is easily illustrated in the example of having one SIM for work, and another for personal use, both controlled in one handset.

These phones, in principle, work exactly the same way as a normal single SIM phone. Your SIM code contains a unique code called an IMEI code, which is used to identify each SIM card.

Dual SIM phones use two separate IMEI numbers to identify each SIM card, allowing a user to have two separate phone numbers, and in some cases, operating at the same time on a single device. More recently, with the introduction of the eSIM, some phones will use a traditional nano-SIM with an internal eSIM to operate and function as a dual SIM phone.

Standard, Nano SIM or Micro SIM: Which do I need?

The SIM card has reduced in size with each consecutive version, culminating in the eSIM, but more on that later. First, lets understand the reduction in size of the SIM card from the early 90’s to the eSIM (2019)

A Subscriber Identity Module, or SIM for short, has been around since the 90’s. It’s most likely that if you’re clutching a phone made since 2010, you’re using a nano SIM. For those of you lucky enough to still have a functional phone pre-2010, you’ll be rolling with a Micro SIM or - worst case - a Standard SIM.

All of these SIM cards do essentially the same thing, they are the identifier

How to check what SIM you need?

The easiest way to check is to open your phone and have a look at the SIM tray size or tray instructions typically found near or on the tray in most smartphones.

The good news is that most networks have been on board with making their SIM cards universally compatible for all models of mobile phone, from the trusty Nokia 3110 (remember those?) to the newest Flagship phone. These are aptly named multi-SIMs and can be modified to suit the tray size of your phone. Check the video below for how to modify a SIM card to suit any phone:


Dual SIM handsets:

There are a number of features which newer smartphones have made redundant nowadays, but there are still some sigificant differences between the two main types of dual SIM handset. One of the most common features is the ability to receive data or messages from both SIM cards. Here's some more in-depth information on the two types of dual SIM handsets:

Dual SIM Dual Standby handsets

A Dual SIM Dual Standby handset is a device that has space for 2 seperate SIM cards built in to the device, but only one of the SIM cards can be operational at any one time. This is perfect for when travelling and you want to use a local network for data, while every now and again, checking for notifications on your normal personal SIM.

The advantage here is that most phones allow you to easily switch from one SIM to the other in the settings section of your phone. It's that simple.

image of a smartphone

DSFA (Dual-SIM Full Active) Handsets

DSFA (Dual SIM Full Active) handsets are a little different to DSDS handsets. The main key difference is that both SIM cards can be active at the same time. This is ideal in a situation where you need to be able to receive notifications from both SIM cards, for example, a personal SIM and a work SIM.

It’s worth checking with the manufacturer’s phone specifications before purchasing to confirm. However, most offer the ability to adjust functionality features within the settings of the phone. You can easily switch between the >data, calls, and texts of two SIM cards with the touch of a button. For example, users can use ‘hot-swap’ which allows them to swap data-use between SIM cards easily.

Dual SIM phone features

With all the different phone settings and features offered by each manufacturer, it can feel like you’re entering a technical double-universe. Let’s clear up that double-vision on the topic with some information on some of the best (and maybe worst) features.

  1. Tariff & SIM flexibility:

    You can use a dedicated SIM card for calls and text messaging and a second sim card as a data-only SIM, each on a dedicated tariff to suit your needs.

  2. Dual SIM for travel:

    There’s also the convenience of using a dual-SIM for traveling, so you can keep your existing SIM contract switched on and use a travel SIM to reply to messages or send those much-loved travel snaps to friends and family while you’re on holiday. Did somebody say selfie!?

  3. Customise notifications:

    Another huge bonus is the customisation of notifications for each SIM card, perfect for differentiating the notifications between work and personal SIM cards. This also works for contact and calendar information should you need to store contact details on a particular SIM card (does anyone do that anymore? Enter stage left: cloud storage!)

  4. Extra storage with SIM ports:

    It’s always best to check the smartphone specifications or technical reviews before purchasing, as there’s often an opportunity for dual-SIM ports to function as additional SD card storage space.

So whether you need a phone that caters for work and personal use, ensuring comprehensive coverage with the use of two separate networks or if you’re looking into a smart traveling option, a dual-SIM phone is a great choice.

You can easily adjust dual SIM setting on your phone within the main settings section of your phone.

Dual SIM Phones UK

Whilst Dual SIM phones are hugely popular abroad, they somewhat lack the attention they deserve in the UK. The main reason for this is likely to be that us Brits, being a little shy on the typical Chinese smartphone purchase, often consider anything other than the flagship iPhone second place.

Foreign smartphone manufacturers such as Samsung, OnePlus, Huawei, Xiaomi and Honor have started to prove themselves worthy - and much more affordable - considerations for consumers They consistently offer a wide array of features including the dual SIM feature. Here’s a few of the best smartphone manufacturers which offer dual SIM phones in the UK.

Samsung Dual SIM

Samsung is by far one of the most popular dual SIM smartphones manufacturers globally. The first Samsung Dual SIM developed by Samsung was the B5722 Duos way back in 2010. It was a sign that dual SIM technology was starting to capture the interest of the purchasing mainstream, but further investment in the dual SIM tech is now evidently paying off, as the company’s most recent smartphone offerings have really brought them the limelight.


Huawei Dual SIM

With over 180,000 employees at the time of writing, of which half are involved in research and development, it’s no surprise that Huawei has been significant in the development of smartphone trends and technologies.

Leaving no stone unturned, Huawei started producing phones with dual-SIM capabilities many years ago. Here are a few examples of the more recent dual SIM offerings from Huawei.


OnePlus Dual SIM

OnePlus, the Chinese smartphone manufacturer based in Shenzhen, China, first made a splash in the international smartphone market back in April 2013 with its OnePlus One smartphone design.

Clever international marketing was accompanied by the slogan ‘Never Settle’ and niche smartphone features, including textured phone case, high-spec front and rear cameras, and the inclusion of dual SIM trays, which can double as extra storage. All of these factors aided OnePlus to hold a strong market share in the budget and mid-priced smartphone sectors.

OnePlus 2 was the first phone in the OnePlus range to support dual SIM functionality. The manufacturer has come a long way now, and in just 6 years it has made a few of the larger international providers nervous with a range of smartphones such as the OnePlus 7T, sporting dual-nano SIM card slots.

Honor Dual Sim

Some of the most affordable dual SIM smartphones on the market are made by the Chinese manufacturer Honor. More focused on the budget and mid-priced market, Honor offers a range of well priced and feature-packed smartphones all with dual SIM functionality. The manufacturer's phones are well built and fully functional in the UK.

Starting out with the launch of the Honor 7A in April 2018, the smartphone manufacturer has now released over 10 other models, most recently the Honor 9, the Honor 9 Lite, the Honor 10 and the Honor 10 Lite, all with dual SIM functionality.

SONY Xperia Dual SIM

The SONY Xperia Dual SIM range of phones continues to expand with every new release by the ever-technically conscious manufacturer. Sony’s slick and uniquely designed phones are fully featured with top-end functionality, even at the lower price-pointed smartphones such as the Sony Xperia R1.

For those with a more generous budget, SONY has some great smartphones available, such as the flagship model - the SONY Xperia 1. Also worth a mention is the highly rated Sony Xperia XZ3 which is slightly more affordable. Both were released in 2019.


Google Pixel Dual SIM

The Google Pixel 2 and Google Pixel 2 XL, both released in early 2017 have Nano-SIM and eSIM capabilities. However, eSIM functionality depends on the Android software you use. For example, Android Q Beta 2 enabled dual SIM support however Android Q Beta 3 disabled it.

The Google Pixel 3, the Pixel 3 XL, and most recently the Google Pixel 4 also tow the same line as their predecessors, having one physical SIM card tray, and one eSIM. It’s worth mentioning, however, that DSDA (Dual-SIM Dual Active) or DSDS (Dual-SIM Dual Standby) are not supported on the entire Google Pixel range of phones at the time of writing.


Apple SIM - at it again

Yep, you guessed it. A little late to the party, nevertheless, Apple provides full steed to express our inner duality as of late 2018. Apple launched a small selection of iPhone handsets featured with dual SIM - well, almost. Cue theatrical music. The Apple SIM was born.

Actually, the iPhone XS and the iPhone XS Max were the first offering dual SIM ‘functionality’ back in late September 2018, with the creatively named Apple SIM. Since then, nearly all models of iPhone have the ability to operate in the same way as a traditional dual SIM handset. But Apple being Apple, it decided to do it differently.


The Apple SIM is an indication of the direction industry leaders will take in developing the next generation smartphone. With the support and cooperation from the telecom industry association body GSMA, Apple will continue to roll out this technology in subsequent releases and will likely omit a physical SIM card in their devices in the future.

This will benefit consumers as it removes the requirement of a mobile network supplied SIM to operate a phone or device. It will also reduce the handset cost due to a reduction in physical parts required. Apple is also cleverly removing the power from a network provider, so it may not be long before we see manufacturers releasing phone plans themselves.

So what’s so different between an Apple SIM and other smartphone manufacturers’ dual SIM offerings?

Embedded SIM, eSIM or Apple SIM?

image of a cartoon man deep in thought

Embedded SIMs (or eSIM for short) are electronic SIMs which do away with the need for physical SIM cards. The main pursuit for this technology can be traced to way back to 2013 and credited to GSM Alliance.

ESIMs allow for remote provisioning to any network, and without the limitations of a physical SIM, the technology can be introduced to smaller devices, such as smartwatches and IoT - the Internet of Things. This will increase the range of products which can be enhanced with connectivity to a mobile network.

Initially a solution to the limited carrier provisioning that restricts the traditional SIM card technology, this tech has been supported by some of the biggest technology manufacturers such as Google and of course, Apple with its creatively named Apple SIM.

VoLTE (Voice over Long Term Evolution)

Some manufacturers allow for both SIMs to operate simultaneously, which uses technology called VoLTE or Voice over Long Term Evolution (similar to VoIP). This technology was acclaimed to be the next progression of mobile phone telephony after 3G. LTE, or more commonly known as 4G in the UK, utilises the LTE radio access technology.

VoLTE allows for voice and data to be sent over a network. LTE, or 4G supports download speeds of 100 Mbps and upload speeds of 50 Mbps. As 4G uses larger bandwidth than a traditional 3G signal, it will provide smoother and more detailed data transfer in both sending and receiving packets of data, meaning your calls will connect faster and sound clearer with less distortion - although the quality of the call will also be impacted by the quality of the handset that is used.

With each succession of mobile network, there’s a huge increase in data transfer speed and remote connectivity, as shown in the chart below:

Network speeds in the UK:
Network Type Avg Download speeds Max Download Speeds
3G 8Mbps 384k
4G 32Mbps 100Mbps
4G+ 40Mbps 300Mbps
5G 130-230Mbps 1-10Gbps

Find out more about 5G in the UK in our What is 5G guide.

The good new is that VoLTE is available on most new handsets and is easy to set up. Simply go into your phone settings, look for Connections: WIFI, data, mobile network - then from there in the mobile network section you will find settings to toggle VoLTE on or off. In some phones it is simply marked as 2G, 3G and 4G connectivity as your preferred network mode.

Dual SIM and eSIM in-contract?

Still in contract? When purchasing a new phone, it’s likely you will purchase a handset which is tied to a contract with a specific mobile network provider. These contracts typically are 12, 18 or 24 months in length and, depending on the contract length, will offer a discounted upfront charge for the handset.

Buyer beware: The contract trap

So, you’ve just signed up to O2 with a brand new iPhone on a 2 year plan, fantastic! and now you want to use dual SIM features on your phone in the UK, but there’s a catch. Your contractually locked into using one network for the duration of the contract, which effectively means you won’t be able to access the benefits of dual SIM or eSIM functionality until the handset fulfills its contract and can be unlocked. So now what? Either wait out the contract or purchase the phone outright to use with SIM only plans

Unlocked Handsets with SIM Only plans

Well, sadly for those who’ve signed up recently and are in contract, you will have to pay out the contract or wait till it’s fulfilled before you can unlock your handset. However, for the increasing consensus of people who are buying handsets outright, they are usually unlocked and not tied to any particular network. This allows you the flexibility of moving from one network to another with ease, not to mention usually saving a few quid along the way.


Are Pay As You Go SIMs Cheaper?

Short answer: Yes. Way cheaper, but not always

It’s no secret that as customer demand increases in the PAYG market, prices descrease and become more competitive. However, as it stands now in the UK, a pay-as-you-go SIM and an unlocked handset are the cheapest ways to get connected, manage costs, and to have the convenience to shop around any time with no ties to a network.

Looking for the best PAYG SIM deals?

The only exception is when some networks offer exclusive contract deals including handsets, but this is rare, so it’s worth doing the sums on any contract costs before locking yourself in for a 2 year ride with any one network.

Summary: Dual SIM for life?

It’s clear there are some fantastic advantages and very few disadvantages to using a dual SIM phone, and as the technology has been available for a while now, it’s not unusual for a budget, entry level smartphone to have dual SIM capabilities.

Here are some of the pros:

  • Business and personal SIM and phone numbers in the same phone
  • Traveling and multiple network provisioning made easy
  • Freedom to switch networks globally
  • A handy back-up for those times you run out of data, texts or calls on one network

Dual SIM devices are likely to become more prominent in the UK as asian smartphone manfacturers become more globally recognised by consumers. Additionally as production costs continue to reduce with eSIM technology, more and more smartphone and device manufacturers will include this feature in its devices.

Looking for a new UK SIM? You can find information on getting a UK SIM in this handy guide.

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