Many users considering buying a smartphone based on Android One or already owning a device often wonder about the support of two SIM cards. Xiaomi Mi A1 has become a landmark device for the company, offering a clean interface without unnecessary shells. However, switching issues remain relevant, especially for those who are used to separating work and personal contacts or using different operators to save traffic.
In this article, we will discuss in detail the technical features of the tray, how to install cards of different formats and the nuances of working in double mode. You will learn how to properly configure the priority slot for high-speed Internet and what to do if the phone stops seeing one of the sims.
Technical characteristics of the Mi A1 slots
Smartphone Xiaomi Mi A1 The hybrid slot is equipped with a hybrid tray, which is an important nuance for understanding the capabilities of the device. SIM-card SIM-You can't use two SIMs and flash memory at the same time, you have to choose between the expansion of memory and the second number.
Both slots support the Nano-SIM standard, which is currently the most common in the world. The card size is 12.3 × 8.8 mm. It is important not to confuse them with Micro-SIM or Mini-SIM, as trying to insert a larger card can lead to mechanical stuck or damaged contacts inside the device. 4G (LTE) support is implemented in both slots, but they can not work at high speed at the same time.
⚠️ Warning: Be sure to turn off the device before removing the tray.Although modern standards allow hot replacement, in the case of Xiaomi Mi A1 This can cause a software failure and the phone won’t detect the SIM card inserted until the next reboot.
Dual SIM Dual Standby (DSDSDS) technology allows both numbers to stay online at the same time. When one SIM card is busy talking, the second one remains available for incoming calls if the operator provides a call-waiting service. However, data transfer can be suspended or switched at this point, depending on the network settings.
Instructions for installing two SIM cards
The process of installing cards in the Xiaomi Mi A1 requires care, as the tray is quite thin and sensitive to distortion. First you will need a special clip that comes with the kit, or a thin needle. The extraction hole is located on the bottom end of the case, next to the USB Type-C connector.
Press the clip in the hole and wait for the tray to pop out. Pay attention to the shape of the cutouts: they have rounds that correspond to the shape of the Nano-SIM. The microSD card is usually installed in the second slot if you do not use the second SIM. Contact pads should look down, and the cut corner of the card should match the pattern on the tray.
☑️ Pre-installing check
Once installed, carefully insert the tray back until the characteristic click. Don't put too much effort; if the tray doesn't come in, it's the wrong side. Turn on the device and wait for the network icons to appear. Usually, the system automatically recognizes both operators and suggests that they be configured.
Setting priorities and the Internet
After successfully installing two SIM cards in the Xiaomi Mi A1, you need to set up their interaction correctly. In the pure Android that is installed on this model, the settings menu is located along the Settings path → Network and Internet → Mobile Network. Here you will see a list of installed cards and their parameters.
The key is to choose a map to transmit data, and because LTE cannot work on both numbers simultaneously, you need to specify which SIM card to use for the Internet, and the second card will then go into 2G or 3G mode to provide voice, which is the standard restriction of chipsets of the time.
- 📶 Mobile data: select SIM-card with the best internet fare or the best coverage in your area.
- 📞 Default calls: Specify which card to make outgoing calls from, or leave the “Always Ask” option to decide this before each set.
- 💬 SMS Default: Assign a primary number to send text messages so you don’t get confused with senders.
Also available in this menu is the function of switching networks. You can configure automatic choice between 4G, 3G and 2G. To save battery power in Xiaomi Mi A1, it is recommended to turn off the search for 5G networks (if such a item appears after updates) or leave only 4G/3G/2G, as the constant search for a non-existent 5G signal quickly puts the battery down.
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Use Flight Mode for 5 seconds if one of the SIM cards is missing after setting up, this will force you to restart the communication modules and update the registration in the operator's network.
Comparison of network modes
Understanding how communication works across different configurations will help optimize smartphone usage. Below is a table showing the distribution of network resources under different scenarios of using two SIM cards in the Xiaomi Mi A1.
| Use case scenario | Slot 1 (Main) | Slot 2 (Secondary) | Internet speed |
|---|---|---|---|
| Both SIMs are active, Internet on SIM 1 | 4G LTE (Data + Voice) | 2G/3G (Voice/SMS only) | High (LTE) |
| Both SIMs are active, Internet on SIM 2 | 2G/3G (Voice/SMS only) | 4G LTE (Data + Voice) | High (LTE) |
| We're talking about SIM 1. | 3G/2G (Voice) | 2G/3G (Waiting) | Low/Not present |
| One SIM (SIM 1 only) | 4G LTE (VoLTE if available) | No signal. | Maximum |
As you can see from the table, when you talk actively on one of the SIM cards, the second one may temporarily lose the ability to transfer data if VoLTE (Voice over LTE) technology is not turned on. In the Xiaomi Mi A1, VoLTE support depends on the operator and the firmware version. If your operator supports this technology, then during the conversation the Internet will not shut down, but will remain at 4G speed.
What is VoLTE and how to turn it on?
Problems with SIM card definition
Users sometimes face a situation where the Xiaomi Mi A1 stops seeing one of the SIM cards or writes "No service" often due to software failure or oxidation of contacts. First of all, try to remove the tray, wipe the SIM contacts with soft dry cloth and insert them back, making sure that the tight fixation.
If mechanical cleaning didn’t work, the problem may lie in network settings. Go to Settings menu → System → Language and input and check region. Sometimes changing region to “USA” or “India” helps unlock hidden frequencies or features that can improve communication stability, although this is rarely required for global versions.
⚠️ Attention: Do not use scissors to trim SIM cards to the size of Nano. the cut is uneven and can damage the contacts inside the slot.
In rare cases, the problem lies in the tray itself, the contacts inside the smartphone may have oxidized or bent, and if the phone falls or falls into the water, even in small quantities, the corrosion of the contacts is a likely cause, and in this case, professional cleaning at the service center is required.
Frequently Asked Questions (FAQ)
Can you insert a memory card and two SIMs at the same time in Xiaomi Mi A1?
Does the Xiaomi Mi A1 support 4G technology on both SIM cards?
Why does the phone not see the SIM card after installation?
How to transfer contacts from an old SIM card to Xiaomi Mi A1?
By understanding switching issues, you can make the most of your smartphone. Xiaomi Mi A1, despite its age, remains a reliable device for everyday tasks, if you properly configure its basic communication functions.
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The main conclusion: Xiaomi Mi A1 supports two Nano-SIM cards, but has a hybrid tray, which does not allow you to use flash memory and two numbers at the same time.