If you have ever paid attention to smartphone specifications, you might have noticed that some mobiles are said to be dual SIM handsets. While it may seem obvious what that means just from the name, there is quite a bit to unpack about the dual SIM technology.
In this article, we’ll look at what exactly a dual SIM phone is, how it works, and some of its advantages and disadvantages.
What is a dual SIM smartphone?
A dual SIM smartphone is a mobile phone that has space to accommodate two separate SIM cards. Depending on the type of dual SIM technology used, the two SIM cards be used together at the same time, even during a call.
Dual SIM smartphones can either have two separate slots for each SIM card, or a single slot with a tray that can hold two SIM cards.
Until recent times, most popular mobile phones globally could only accommodate one SIM card at a time. However, this technology has been around for a long time in certain markets around the world.
Mobile service providers have been known to be against the idea of dual SIM smartphones because of the impact it will have on profit. Consumers using dual SIM smartphones would be able to have one mobile phone instead of two. And not only that, they could use a competitor’s SIM card in the phone, too.
However, due to demand, the tide is turning. More and more smartphone OEMs (original equipment manufacturers) are adding dual SIM capabilities to their smartphones across the globe.
How does it work?
Dual SIM smartphones do not all work the same way. There are two common versions of this type of technology that can be found on smartphones– the standard dual SIM version and a hybrid dual SIM version.
Not only that, the actual way in which the phone operates the two SIM cards differs from phone to phone. That depends on whether the smartphone uses passive or active dual SIM technology.
Types of dual SIM technology
Passive dual SIM technology only allows for the use of one SIM card at a time and is, therefore, not popular. Active dual SIM technology which is used in many smartphones, on the other hand, allows you to you use both SIM cards in two different ways– dual active and dual standby.
Dual SIM Standby (DSS)[Passive]
Dual SIM standby is the only passive type of dual SIM technology found in smartphones. Although a phone using this technology can have two SIM cards inserted inside it, it can only use one at a time. The other remains unavailable until it is manually activated after deactivating the first.
You cannot use both SIM cards at the same time. For this reason, it is not very popular in smartphones these days.
Dual SIM Dual Active (DSDA)[Active]
A dual SIM dual active smartphone is the complete opposite of the dual SIM standby technology. With DSDA, both SIM cards remain active the whole time. This means that you can get notified of an incoming call on one SIM card while you’re still on a call on the other. You can even combine the calls from different SIM cards to make a conference call.
But as cool as they sound, dual SIM dual active smartphones aren’t the most popular on the market. That’s because each SIM card has its own transceiver system for connecting to a mobile network provider. This drives the cost of production up, making the device more expensive.
Dual SIM Dual Standby (DSDS)[Active]
This is the most commonly found type of dual SIM technology found in today’s smartphone. With dual SIM dual standby, both SIM cards can be reached as long as they’re in standby mode and not in use. If you’re using a 2G network, then one number becomes unavailable when you’re on a call on the other.
But this is not a problem if you’re using 3G, 4G, or 5G. If you’re making voLTE calls, then you can still get notified of an incoming call on the other SIM card. However, you cannot combine calls from both numbers to create a conference call.
Dual SIM variations and unequal connectors
When talking about dual SIM smartphones, it’s easy to imagine a phone that has two identical slots for SIM cards. Though that image would not be wrong, there are other dual SIM variations that can be found in different phones on the market.
The three most common other variations of the dual SIM technology are:
Hybrid dual SIM
A hybrid dual SIM smartphone has two slots for two SIM cards. The first slot is dedicated to the primary SIM card, however, the second slot can either accommodate a SIM card or a memory card. So, in essence, a hybrid dual SIM mobile phone can operate either as a dual SIM phone or as a single SIM phone with an external storage slot.
Multiple SIM size
If you are at all familiar with SIM cards, you’ll know that they’re not all the same size. Some phone manufacturers kept that in mind and factored it into the design of their dual SIM technology. The results were phones that could accommodate two SIM cards of different sizes.
A variation of the multiple SIM size technology is one that includes an embedded SIM card aka eSIM. As the name suggests, an eSIM is part of the phone and cannot be removed from it. So, if the phone is a dual SIM smartphone that has an eSIM, usually only one SIM card (the “normal” one) can be removed and replaced. There are phones that have a hybrid dual SIM setup plus an eSIM.
4G+2G and Dual 4G
Some phones offer different connectivity on each SIM slot. It’s not uncommon to find a dual SIM phone that has 4G connectivity on one slot and 2G connectivity on the other. You also get slots with the same connectivity such as dual 4G.
Pros and Cons of dual SIM smartphones
There are some considerable advantages and drawbacks of dual SIM smartphones. But because, in principle, all dual SIM smartphones work the same, the advantages are very similar and shared. The disadvantages are more evident in their differences.
Advantages
The greatest advantage of a dual SIM smartphone is obviously the ability to use two SIM cards on the same device. This is great especially for people who have a business number and a private number for family and friends.
Another benefit of a dual SIM smartphone is evident when travelling. When you’re in a foreign country, you can use the second slot to insert a SIM card from your destination country. This can save you quite a lot on roaming charges.
Some markets have mobile service providers with uneven costs for calls and data. Some service providers have cheaper voice packages while other providers have better data deals. If you live in such an area, it would be beneficial to have two SIM cards from different service providers in order to get the best of both worlds.
Disadvantages
A great disadvantage of a dual SIM smartphone is that you may not be able to use both SIM cards at the same time. Depending on whether the phone is DSDA or DSDS, you might be restricted in terms of how much you can use both SIM cards simultaneously.
Another disadvantage of dual SIM mobile phones is that they generally tend to use up more battery, especially the dual SIM dual active type. That’s because of the power it takes it to run two transceivers simultaneously.
In the case of a hybrid dual SIM smartphone, a big drawback is that you can’t use a memory card for extra storage should you choose to use two SIM cards at the same time.
Dual SIM adaptors
Although dual SIM smartphones are more common today than they were many years ago, there is still a significant number of phones that have a single slot for one SIM card only. Using a dual SIM adaptor allows such phones to also be able to use two SIM cards, just like any other dual SIM smartphone.
How it works is that the adaptor is inserted into the slot where the SIM card would normally go. Connected to the adaptor chip is a thin, long, strip that has a SIM card holder at the end with space for two SIM cards.
Passive dual SIM adaptors require you to manually switch between the two SIM cards, while, on the other hand, active dual SIM adaptors allow you to use both SIM cards simultaneously.
Conclusion
Dual SIM smartphones are very useful, particularly if you travel to other countries a lot or you need to use two numbers but don’t want to carry around two phones.
However, if you’re looking to buy a new smartphone and using two SIM cards is important to you, make sure you get one with the right technology for you to avoid disappointment. You wouldn’t want to be stuck with a hybrid dual SIM smartphone while you have two SIM cards and a memory card you use often.
