A modern smartphone is impossible to imagine without stable access to the mobile network, and for many users, having two numbers is a critical condition when choosing a device. Xiaomi Mi 9T, also known as the international name Redmi K20, has become a hit due to its frameless design and powerful stuffing, but it is communication issues that often cause the most controversy among potential buyers.
In this article, we will discuss in detail how many SIM cards Xiaomi Mi 9T supports, what are the limitations on sizes and how to properly install memory cards without compromising the second SIM. You will learn about the nuances of working two networks simultaneously, support for modern communication standards and get practical tips on setting call priorities.
Understanding the design of the tray for SIM-cards will allow you to avoid common errors in operation and maximize the use of the capabilities of your smartphone. We will consider not only the physical characteristics of the slot, but also the software features of the shell. MIUI, which regulate the operation of communication modules in different modes.
Tray design and physical sizes of cards
The basis for understanding connectivity is the physical design of the tray, which is located on the bottom end of the device. Xiaomi engineers hybrid circuit, which means that there are two seats, each of which has its own characteristics and compatibility limitations. In the tray you can install two Nano-SIM cards, which is the modern standard for most flagship and sub-flagship devices.
Importantly, using a second slot often becomes a choice between a memory extension and a second SIM card, a classic dilemma for hybrid tray owners that requires pre-configuration planning. If you plan to actively use multimedia files, apps and games, you may not have enough built-in storage, and then you will have to sacrifice the second number.
To remove the tray, you need to use a special paper clip included in the delivery, or a thin needle. The pull-out mechanism works smoothly, but requires care so that you do not damage the internal contacts or the tray body itself. You should not make excessive efforts, as this can lead to a breakdown of the mechanism.
Owners of old cards of the Micro-SIM or Standard-SIM format will have to contact the communication salon for a free replacement with Nano-SIM. It is strongly not recommended to trim the card yourself, as you can damage the chip or disrupt the geometry, which will lead to getting stuck in the slot.
⚠️ Warning: Avoid installing cards that have been physically cropped with scissors or using templates.Such cards often have uneven edges, which can lead to a jamming tray inside the Xiaomi Mi body 9T It will require expensive repairs at the service center.
The hybrid slot is a compromise solution that allows you to save the thin body of the smartphone. In the Mi 9T, this compromise is implemented quite competently, but requires the user to make an informed choice of priorities, you must decide in advance what is more important to you: the second number or gigabytes of additional space.
Support for two SIM-maps and modes of operation
Smartphone Xiaomi Mi 9T fully supports the work of the two SIM-The card system simultaneously allows the user to receive calls and messages to both numbers without having to switch. SIM Dual Standby (DSDS), This ensures that both numbers are always ready to receive incoming calls.
But you have to understand the difference between standby and active use of communication channels, and while you're not talking, both SIMs are active and logged in, but when you start a conversation on one line, the second line goes into standby mode or becomes unavailable for voice calls, depending on the operator's settings and support for VoLTE technology.
To manage two numbers, the system has a user-friendly interface that allows you to flexibly adjust preferences. You can assign one SIM for mobile Internet, and leave the second one exclusively for voice and SMS. This is especially true if operators’ rates vary greatly in terms of traffic and minutes.
- 📱 Basic SIM: is used by default for all outgoing actions unless otherwise selected.
- 🌐 SIM Data: map through which the Internet is accessed (3G/4G).
- 📞 SIM for calls: you can configure the choice each time or fix a permanent card.
- 💬 SIM for SMS: separate setting for sending text messages.
Priority settings are done through the Settings menu → SIM-Maps and mobile networks, where you can write down the device's behavior in detail for each specific use case, and it allows you to quickly switch between profiles, which is convenient for roaming or changing tariff plans.
Support for 4G LTE technology on both SIMs is particularly noteworthy: while only one card can operate at high speeds at the same time, the second card can also register on fourth-generation networks to receive calls, which provides more stable connection and quick switching between communication standards.
Problem of choice: Second SIM or MicroSD memory card
As mentioned, the tray in Xiaomi Mi 9T
For users who are critical to all three, there are alternatives, such as using cloud storage for photos and documents to free up internal memory, and many modern services allow you to move most of the data online, minimizing the need for a physical map.
If you have huge archives of high-resolution video or music libraries offline, then the second SIM card might be worth it, and a 256GB or 512GB MicroSD card would be a great addition to the built-in 64 or 128GB of memory, and the speed of reading modern cards allows you to run even some applications and games from them.
| Configuration | Slot 1 | Slot 2 | 4G support |
|---|---|---|---|
| Two. SIM | Nano-SIM | Nano-SIM | Both (in turn) |
| One SIM + SD | Nano-SIM | MicroSD | One active. |
| One SIM | Nano-SIM | Empty. | One active. |
| Only SD. | Empty. | MicroSD | No network. |
When installing a memory card, the system automatically reconfigures the file system. Always use the Safe Retrieval feature or turn off the phone before changing the media.
Setting Priorities and Traffic Management
Effective two-number management requires a good setup of the software. The MIUI shell on the Xiaomi Mi 9T offers advanced tools for controlling costs and traffic. You can set data consumption limits for each SIM separately, which will help avoid unexpected bills from the operator.
The settings menu includes the Traffic section, which provides detailed statistics, and the system can automatically limit background data transfers for the second SIM if it is only used for rare calls, which significantly saves battery life and prevents the applications from consuming traffic background.
For outgoing calls, you can configure three main modes: always ask, use the default primary SIM or remember the choice for each contact. The latter option is the most convenient, since it allows you to assign a certain number to important contacts, and the phone will offer the desired SIM when dialing.
- 🔔 Indication: The status bar displays two network icons showing the signal strength for each card.
- 🎨 Color coding: When an outgoing call is made, the screen is colored assigned to a particular SIM, which helps not to get confused.
- 🚫 Blocking: You can temporarily disable any of the SIMs software without physical extraction.
Special attention should be paid to the function "Data Switching". If the main SIM, through which the Internet goes, the smartphone can automatically switch the mobile Internet to the second SIM, this option must be activated manually if it is not enabled by default, as it can lead to traffic consumption from the paid tariff.
⚠️ Attention: Be careful with the automatic Internet switching feature in roaming. If you are abroad, accidentally activating data transfer via a second SIM can lead to very high roaming bills.
The Impact of Two SIMs on Autonomy and Communication
Using two active SIM cards inevitably affects the power consumption of the device. The communication module must support network registration for two different operators, which puts additional strain on the processor and radio module. Owners of the Xiaomi Mi 9T may notice that when two SIMs run, the battery discharges about 10-15% faster than when using one.
The impact is particularly noticeable in areas of uncertain reception, where when a phone is constantly searching for a network or switching between base station towers for two numbers, the energy costs increase many times, and in such situations it is wiser to leave only one main SIM or turn on flight mode for a second one if it is not urgently needed.
Communication quality can also vary depending on the frequency load and the interaction of the modules. Although the Mi 9T is equipped with high-quality antennas, in rare cases users notice slight interference or heating of the lower part of the body during long conversations with active Internet on the second SIM.
To optimize your work, it is recommended to periodically reboot your smartphone, especially after traveling to areas with poor coverage, this helps communication modules re-register on the network and choose the optimal frequencies for work.