Dual sim: how does that work?
When do you use dual SIM?
Dual SIM comes in handy in various situations. Think for example of business use; you can separate your private life and your business, without needing an extra phone or having to switch between SIM cards all of the time. On top of that, you can reap a lot of benefits from the dual SIM when you're abroad: use a local SIM card alongside your regular SIM card to reduce costs. Since roaming costs no longer apply to the European Union, this is mainly true for far destinations.
Active dual SIM: 2 antennas, always available
Active dual SIM devices have 2 antennas: one for each SIM card. In fact, it's two phones in one. This means the SIM cards can work separately from each other and 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 SIM card and use only one at a time. Active dual SIM is quite rare, since it's difficult to integrate two antennas at the same time.
Standby dual SIM: one antenna, not always available
Most dual SIM devices are so called standby types. These devices only have one antenna. This means that you can't use both SIM cards at the same time. As long as you're not calling, texting, or using the internet, you're available on both SIM cards. If you 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.
The eSim is an integrated 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. To use eSim, both your smartphone and your provider must support eSim. Currently, there aren't many providers that offer eSim, so check this well in advance.