What is Dual SIM and Why Get a Dual SIM Phone?

|What is a dual SIM phone

If you’ve been in a mobile phone store lately, chances are you’ve seen a few smartphones with dual SIM technology. So, what is a dual SIM phone, and why is it useful to have? What are its advantages and disadvantages?

A dual SIM smartphone is one that is capable of using two different Subscriber Identification Module (SIM) cards at the same time. Essentially, this means you can have two phone numbers and two phone plans from two different mobile providers work on a single phone.

What are the benefits of dual SIM?

Dual SIM smartphones are probably most useful for people tired of carrying around two different phones everywhere for their work and personal life or frequently travel to areas not covered by their main carrier service. Instead, dual SIM offers one phone with two phone numbers active on it.

A dual SIM smartphone is also a huge benefit for getting the best value from multiple service plans. Some phone service providers have a great voice or long distance plans but charge too much for data, while others might offer great data rates by expensive voice plans. With a Dual SIM, you can pay for the best deals from both without having to get a mediocre full-service plan. This also works well if two different providers have complementary voice and data coverage for your area.

Travellers, particularly people who travel frequently for business are another example where dual SIM smartphones make sense. Step off of a flight or train and you’re already on a local network without having to worry about roaming fees, and no fiddling to eject and swap SIMs in airports or taxis!

Types of dual SIM phones

There are a few different kinds of dual SIM phones, each with advantages and disadvantages:

Important note: To use dual SIMs, a phone with the technology must be unlocked.

Dual SIM Single Standby – the oldest kind of dual SIM. This type of phone holds both SIM cards, but only one can be active at any time. You need to manually change which is used. This is effective if you know you’ll only need to be reached on certain days, or if you’re travelling often between countries. It is rare to find this in smartphones, but you might find it with other kinds of phones.

Dual SIM Dual Active – unlike Dual SIM Single Standby, phones with this keep both cards active at the same time. If you’re taking a call with one SIM, you will still get call waiting and data from the other. The downsides of this kind of Dual SIM is that to make it work, the phone needs two transceivers, one for each card. This will drain your battery more rapidly, and phones that have this, tend to be more expensive.

Dual SIM Dual Standby – You’ve probably already figured it out – this kind of smartphone can have two cards active with only one transceiver. While they are both in standby, you can take calls with either. Once you take a call, the card not in use deactivates until you end the call. This is only a limitation of phones using 2G to make voice calls (3G and 4G don’t have this limitation). This is probably the most popular form of dual Sim technology in current smartphones and is less expensive than Dual SIM Dual Active.

Popular dual SIM smartphone models

(as of July 2020)


XS, SX Max, XR, 11, 11 Pro Max


P20 Pro, Mate 20 Pro


Galaxy Note 9, Galaxy S9, Galaxy S8


Pixel 3




Moto G5, G6

Getting an unlocked, dual SIM smartphone is not a cheap proposition, and it takes some research to choose two different phone plans that will work well together (not to mention the cost of two plans). While a dual SIM phone might make sense for frequent travellers, heavy data users, or people who straddle borders, it can be an expensive solution, especially if you only need a second number occasionally.

Did you know?

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