Two phone numbers for just one smartphone – this option is offered by dual SIM. But for whom is such a phone worthwhile and what are the technical features? TECHBOOK explains what to look out for when buying.
Dual SIM smartphones used to be scarce. In the shops you had to look for the mobile phones with two SIM slots. But that has now changed. The reasons are, among other things, the widespread smartphones from China, in which the dual SIM function has long been standard, and the introduction of new technologies. But even if a device is called a dual SIM smartphone, there are sometimes big differences between the models. TECHBOOK explains what they are.
What is Dual SIM?
If you need two different mobile phone contracts for making calls – for example a professional and a private one – you have three options. He can constantly change the SIM cards in his smartphone, which is unwieldy and annoying. He buys a second smartphone, which is expensive. You also have to carry two cell phones with you at all times. Or he buys a dual SIM smartphone.
A conventional smartphone has a slot for the SIM card on the side. But there are also smartphones that have two slots: dual SIM smartphones. So you can use two SIM cards or two mobile phone contracts with one cell phone.
These models exist
Dual SIM phones are available both as classic cell phones and as smartphones. The latter have become significantly more relevant on the German market over the past four years. Huawei in particular had a major impact on the increasing spread of dual SIM smartphones in Germany. The manufacturer’s devices often came with two SIM card slots as standard. Other Android manufacturers now also offer a large selection of dual-SIM smartphones. The models are represented by almost all major brands such as Samsung, Xiaomi, Motorola, Nokia and Sony. Even Apple is now using dual SIM for its iPhones – however, the manufacturer uses a special solution here. More on that below in the message.
For whom is a dual SIM smartphone worthwhile?
A dual SIM smartphone, for example, allows private and business connections to be operated in one device. A mobile phone with two SIM cards is also recommended for commuters between two countries or people with relatives abroad. For example, a foreign and a German SIM card can be operated in parallel. This helps to reduce costs.
All devices allow quick switching between the two connections. In the settings under “SIM” or “Network”, the active number for phone calls, SMS or mobile data can be selected using the slider. When making a call, users can also select the number from which they want to start the call at the touch of a button.
Owners of a dual-SIM smartphone can always be reached equally on both numbers. Unless they turn off a SIM card at certain times. This is particularly useful for SIMs used for work. The call notification conveniently shows which phone number a call is coming from.
The differences between dual SIM smartphones
Depending on the model, users have to live with the technical limitations of their devices. Because not every dual SIM smartphone has the same structure. Especially with older models, there can often be differences between the two slots. For example, the fast data connection via LTE is only possible with some via the main SIM. Something similar can currently be found in some 5G smartphones with dual SIM. The fast data standard is not always supported here on both SIM card slots.
There are also differences in the slots themselves. There are three types of dual SIM smartphones:
- Real dual SIM: Such smartphones have a separate slot for each SIM card and also have a slot for a micro SD card for memory expansion. All three cards can be operated separately from each other.
- Hybrid SIM: A hybrid SIM is a slot in which the second SIM card shares the space with the memory card. So users have to decide whether they want to operate a second SIM card in the dual SIM smartphone or whether they want to expand the memory.
- Dual SIM via eSIM: This dual SIM solution is the latest way of realizing a dual SIM smartphone. Devices equipped in this way only have a physical SIM card slot, but allow a second SIM to be operated on the device using an eSIM (digital SIM). Prominent representatives of this solution are, for example, Google with its Pixel smartphone and Apple since the iPhone XS. The data for the SIM cards is usually transferred to the device via a QR code that users receive from their mobile phone provider, provided that they offer an eSIM solution.
With all variants, it should be noted that the simultaneous operation of two mobile phone connections requires more energy than a single SIM device. This can lead to slightly shorter operating times.
Also read: The 4 most important questions about the SIM successor eSIM
What about messenger apps?
Messengers like WhatsApp or Signal identify users by their phone number. However, apps can only be installed once per phone. In order to be reachable via WhatsApp under two numbers at the same time, dual SIM users have to make do. More and more smartphones have the so-called app twin or app clone function. It creates a copy of an app so that a second account can be created.
Another solution is to create a second user account on newer Android smartphones. Here, however, you have to switch between the accounts in order to use the other telephone number.
Read the device description carefully
What a dual-SIM phone really offers in terms of performance should be checked by users before they buy it. For example, which functions the individual slots have, whether they are hybrid slots and also which radio bands the phone covers. Since the information on the packaging is often not sufficient, an internet search helps. The device name and the search term “technical details” or “specs” usually lead to the manufacturer’s website. There is more detailed information there.