Dual SIM technology allows you to keep two SIM cards in the same smartphone but they can not always be active at the same time. There are several types.
There are differences between the technologies Dual SIM Standby, Dual SIM Full Active and Dual SIM VoLTE, the most popular in Italy are the first mentioned, the other smartphones are able to combine two phones with two different users in a single body and at the same time. The Dual SIM Standby instead are those that can accommodate two different cards but can only be active one at a time and not simultaneously. The Dual SIM VoLTE requires a separate discussion that must be deepened.
Smartphone Dual SIM, what it is
The Dual SIM smartphones are those devices that have a dual slot to be able to insert two cards with two different numbers at the same time. They are very useful, for example, to keep in one phone both your work and private numbers, or even two SIMs that belong to different countries or even two SIMs that have two different operators and different offers and pricing plans.
The difference between Dual SIM Standby and Full Active
The difference between Dual SIM Standby and Full Active technology, which we can also call Dual Active, we understand immediately from the names. The first in fact gives the possibility to keep both numbers of the two cards active at all times and then you can receive messages and calls. What happens, however, when one of the SIM is active is that the other in the meantime just goes into standby and can not connect to the network, for example when you receive a call on the other number.
What about the Dual SIM Full Active is instead a technology that allows the integration of two phones within one. In fact, the phone has two antennas and two slots for the SIM, as well as all the necessary hardware components to receive calls and messages and be connected to the network. What happens then is that the moment you receive a call, the other SIM remains potentially active and receptive, without being put on standby.
This doesn't mean that you can talk at the same time with two people calling on two different numbers and with the same phone, of course, but you have different options, such as switching from one call to another without losing the line. Also, if you are talking to one person, you can pause the conversation momentarily and initiate the call to another number, everything is possible on the same and unique Dual SIM Full Active cell phone.
The two types of Dual SIM phones also have a big difference in configuration. In fact, the Full Active does not require you to choose a preference between one card and the other for internet or calls, because both are active at the same time. Instead with the Dual SIM Standby you have to go through the settings menu to manage the dual card. This way you can select which SIM to use for data connection and which one for calls.
Today, the Dual SIM Full Active technology, also called Dual Active, which precisely allows you to use both numbers at the same time, is now available on more latest generation smartphones than some time ago. The most recent ones are Huawei P9 and P9 Plus, Huawei Mate 8, Asus Zenfone 2 and 2 Deluxe and Honor 8, date back to last year, because in 2019 there are still no Dual SIM Dual Active smartphones on the market, many instead Dual SIM VoLTE.
Dual SIM VoLTE, what it's about
The meaning of the acronym VoLTE first of all means Voice over LTE and stands for the technology that allows you to make phone calls through 4G networks for higher listening quality due to the availability of a wider bandwidth spectrum. Even the sound transmission is cleaner and sharper, eliminating background noise to improve communication.
The smartphone, to accommodate the Dual VoLTE must obviously be Dual SIM and also the two cards that are inserted must belong to operators who can offer Voice over LTE, for example in Italy is possible with Vodafone and TIM. You must therefore be able to hook into the 4G network. This technology is advantageous because it can be used on both SIM slots so you don't have to give up 4G connectivity on either card.