What's dual SIM and what can you use it for?

A dual SIM phone has room for 2 SIM cards. Place the 2 SIM cards in your smartphone so you can be reached on 2 different numbers. Before purchasing a dual sim device, ask yourself the following:

• When do you use dual SIM?
• Do I want active dual SIM?
• Do I want standby dual SIM?

Dual SIM is useful in all kinds of situations. Think of:

• Business use: keep your personal and business calls separate without an extra smartphone or switching out your SIM card every time.
• In a foreign country: your phone plan doesn't work in countries outside of the European Union. So you can use a local SIM card in addition to your own SIM card to save money.

Active dual SIM smartphones have 2 antennas: one for each SIM card. In fact, it's two smartphones in one. This means Active SIM cards can work separately from each other, so you're available at all times on both SIM cards. If you're using the internet on SIM card A, you can still receive a call on SIM card B. You can also easily turn off one of the 2 SIM cards. Active dual SIM is quite rare, as it's difficult to build in 2 antennas at the same time.

Most dual SIM smartphones are so called standby types. These devices only have 1 antenna. This means that you can't use both SIM cards at the same time. You're available on both SIM cards as long as you're not calling, texting, or using the internet. If you do want to make a phone call, text, or use the internet, this SIM card uses the antenna of the device. The second SIM card can't be used for the time being. Done? You'll be available again on both SIM cards.

An eSIM is a built-in SIM card. Because it's incorporated in your smartphone, you no longer need a plastic SIM card. You can have multiple phone plans on the eSIM, so you use your smartphone as a dual SIM device. Both your smartphone and your provider must support eSIM. Currently, there aren't many providers that offer eSIM, so check this in advance.