H Yamane 5G

This article is based on an article from the Japanese edition of Engadget and was created using the translation tool Deepl.

DSDS (Dual SIM Dual Standby) , which allows you to put two SIMs in a SIM-free smartphone, is becoming more and more common these days. The early models that came out were a combination of 4G + 3G or 4G + 2G, with 4G communication only available on one side of the SIM, but now almost all DSDS smartphones are dual 4G .

In 2020, 5G service has finally started, and even with that 5G, dual-SIM smartphones are now available. The latest 5G smartphones such as the Samsung Galaxy and Huawei are already DSDS models overseas, but they are a combination of 5G and 4G and only have 5G communication on one side. However, there are already 5G+5G dual-SIM enabled smartphones on the market.

As of the end of June 2020, smartphones that support dual 5G SIM standby are equipped with MediaTek's Dimensity 1000+ or Dimensity 820 chipset. Vivo's iQOO Z1 (Dimensity 1000+) and Xiaomi's Redmi 10X 5G and Redmi 10X Pro 5G (Dimensity 820) are available on the market.

The Redmi 10X 5G / 10X Pro 5G is currently dual 5G+4G, with support for 5G+5G coming in a firmware update.


I used the iQOO Z1 to test out a 5G dual-SIM environment in Hong Kong, where I live. In Hong Kong, all four carriers offer 5G service. I used the 5G SIMs of two of them, China Mobile Hong Kong and SmarTone, with which I have a contract. The actual 5G speeds of these two companies in the city of Hong Kong range from 300Mbps to 600Mbps downstream.

Both carriers have relatively wide 5G coverage, extending to downtown areas and residential areas. However, neither of the two carriers had good signal sensitivity in a limited number of locations. This time, I tested in Causeway Bay, one of Hong Kong's downtown areas. It is a place near the SOGO Hong Kong Department Store. Next to the antenna pictogram on the standby screen, there are two 5G signs, "5G" and "5G".


You can switch which carrier's SIM is used for data communication from the settings screen. This is no different from 4G dual-SIM smartphones. The iQOO Z1 allows you to give each SIM a name, but when you insert the SIM, the name is set automatically. The SmarTone SIM (SIM slot 1) remains defaulted to "SIM1". The China Mobile Hong Kong SIM (SIM slot 2) is automatically named CMCC (CMCC stands for China Mobile, the parent company of China Mobile Hong Kong, which serves mainland China).


First of all, I tested with SmarTone. It was 313Mbps downstream and 70Mbps upstream. Switching to 4G for comparison, I got 32.2Mbps downstream and 18.8Mbps upstream, which I did a few times. is generally around this number.


Next, we switch to China Mobile Hong Kong. 351Mbps downstream and 71.7Mbps upstream. 19.6Mbps downstream and 22.5Mbps upstream on 4G. So both 5G speeds are about 10 to 20 times faster than 4G.


Switching between the two carriers' data transmissions on the iQOO Z1 is instantaneous, and once you change carriers from the settings screen, the signal disappears, but is immediately reconnected. This means that if you have 4G on one side, or if you think that 5G is not sensitive enough, you can instantly switch to the other 5G SIM.

So what are the benefits of 5G dual-SIM support in smartphones?

In Japan, there are not many places where 5G can be used, so we are not yet in a situation where 5G is used in real life. So many people may think that 4G is enough. I'm so used to living on 5G all the time in Hong Kong that I can't see myself going back to 4G any longer.

The characteristics of 5G are described by Huawei as "10 Gbps speeds", "100 billion connections" and "ultra-low latency of 1 millisecond". One of the benefits that the average consumer will find in this is high-speed communication.

Many people already use streaming services for their music and videos. In the 3G era, you would buy music online and download it to your smartphone. But in the 4G era, streaming music has become the norm.

And video viewing has also become a natural part of 4G, with streaming services such as YouTube and Netflix. However, with 4G, depending on your network environment, you may have to wait a little longer to start playing the video or to postpone the scene you want to watch. If all the passengers on the train were to watch YouTube, they would be forced to watch it in low quality because their connection capacity would not be able to keep up.

With 5G, the communication lines are faster and the latency is greatly reduced, which makes it more responsive. When watching YouTube, you can tap play and it will start playing instantly, and if you want to see the scene ahead, swipe the time bar underneath the video to instantly preview the video, and then fast-forward or rewind. You can use YouTube as if the videos were stored on your smartphone.

Also, nowadays, everyone is streaming videos and uploading videos to YouTube. With 4G, the quality of the video may be lowered in the delivery due to the slow connection speed, and uploading can take a long time. It is still difficult to send videos without a fast Wi-Fi environment. But with 5G, you will be able to stream and upload videos more comfortably.

But the 5G area is still small. There is no overlap in the area covered by each carrier, it could be that at one station you can only use 5G on carrier A and another station you can only use 5G on carrier B.

With a 5G+4G dual-SIM smartphone, you won't be able to tell if you are in an environment where "5G for X carrier and 4G for Y carrier" or "5G for both X and Y carriers". With a 5G dual-SIM smartphone, however, you'll know if both carriers are 5G.

There will be more and more occasions in the future where you will need a fast connection, such as when you attend online events or meetings for work. A 5G dual-SIM smartphone is a more reliable way to use 5G in remote environments. As the 5G area gradually expands, 5G usage will become the norm. When that happens, using 4G in non-5G areas will be stressful.

So a 5G dual-SIM smartphone can make up for the narrower 5G coverage of a carrier with two 5G SIMs from two different companies. While few users may need it, it could be useful for business applications that require a fast environment at all times.

Related Article (Japanese):

A dual-SIM phone with 5G support is now available from Xiaomi. Starting at about 24,000 yen

This article is based on an article from the Japanese edition of Engadget and was created using the translation tool Deepl. The Japanese edition of Engadget does not guarantee the accuracy or reliability of this article.