Modern smartphones, including the popular Xiaomi Redmi 9, are often perceived by users as devices that work exclusively out of the box. But when you have to send a message, and it gets stuck in the status of "Send" or comes back with an error, you have to look deeper, and most often the problem is not the hardware failure, but the incorrect parameters of the SMS center (SMSC), spelled out SIM-map or lost after system update.
The messaging center number is the technical gateway through which all your text messages pass before delivery to the recipient. If this number is incorrect, the phone simply does not know where to transfer data. On MIUI devices, access to these settings can be hidden or changed compared to standard Android, which causes difficulties for owners.
In this article, we will discuss in detail how to check and change the settings of the SMS center on Redmi 9. We will consider both standard methods through the engineering menu, and the use of special codes, as well as touch on issues related to the work of the two SIM-The correct configuration of these parameters often solves the problem without going to the service center.
What is the SMS number and why change it
Short message service center (SMSC) — It's a part of the infrastructure of a cellular operator, and it's designed to store and forward messages if the recipient subscriber is currently unavailable or off, and your Xiaomi Redmi 9 needs to know the exact address of that center to work properly. Usually the number is written automatically at the first installation. SIM-maps, but there are exceptions.
Situations where manual (intervention) is required arise when changing the operator while maintaining the number (MNP), corporate SIM-maps or after resetting network settings, and the failure can occur when the device is flashed to the global version. MIUI In these cases, the phone tries to send a message through the wrong gateway, and it gets rejected.
It is important to understand that the number of the SMS center is unique for each operator and region. MTS, Beeline, Megafon or Tele2 In Russia, these figures will differ. SIM-The other card will lead to a guaranteed delivery error. Below is a table with current numbers for the main operators of the Russian Federation:
| Operator. | SMS center number (format) | Note |
|---|
| MTS | +79168910000 | Standard number for the Russian Federation |
| Beeline | +79037000100 | Works in all regions |
| Megafon | +79262000100 | The main gateway of Moscow and MO |
| Tele2 | +79201230100 | It may vary by region |
| Yota | +79990000700 | Using the Megafon network |
⚠️ Note: Enter the number of the SMS center in the international format (with a sign «+» and country code) is a requirement for correct operation in networks 4G/LTE on the Redmi 9.
📊 What is your main communications operator?
MTS
Beeline
Megafon
Tele2
Yota
Other
Before you make changes, you need to know what number SMS center is now registered in your Xiaomi Redmi 9. MIUI There's no direct access to this field through the normal message settings. We'll need access to the engineering menu or use special messages. USSD-if the operator supports them.
The most reliable way is to use a hidden test menu. To do this, open the Phone app and dial the combination ##4636##. If the menu opens, go to Phone Information. Here, scroll down, you can find the SMSC field. However, on some versions of MIUI 12 and MIUI 13 installed on Redmi 9, this field may be hidden or inactive for editing.
If the standard code doesn’t work or the menu is empty, try an alternative path through the settings. SIM-Go to the settings. → The phone. → All parameters. → Status SIM-This sometimes shows the current status of the network, but direct entry of the message center number is rare, and in such cases, third-party applications or special update codes come to the rescue, which will be discussed below.
What happens if the 4636 menu doesn’t open?
On some global firmware, the engineering menu is closed. In this case, try entering the code ##3646633# (MediaTek Engineering Mode), since Redmi 9 is built on the MediaTek Helio G80 platform. Be careful: if an unknown setting in this menu is changed, the radio module may work, another method of checking is sending a test message to yourself. If the message leaves but does not come, or comes with a delay of several hours, this is a sure sign of routing problems through the SMS center. Also note the envelope icon: if there is an exclamation sign next to the message, it is an exclamation sign on the network, or if the Redmi number on the network, it confirms that the error at the network, or the number on the network, if the Redmi number is not confirmed that the number on the network, or the number on the network, it is empty. On Xiaomi smartphones with MediaTek processors, which includes Redmi 9, there are several ways to do this. USSD-To begin with, try the universal method of requesting settings. Open the dialer and type in a code specific to your operator, or try a standard request for profile updates. Often, a simple restart of the communication module helps: Turn on and off "Flight Mode." If that doesn't work, move to manually input. To manually modify, we may need an Engineering Mode app. MTK) Google Play, if the standard means MIUI They block access. Once they install the app, they block access: 📱 Launch the app and select the "Telephony" tab». 📡 Press on «SMS» or «SMSC Setting». ✍️ In the input field, enter your operator number in an international format (for example, +79168910000). 💾 Click the “Set” or “Update” button to save the settings. ⚠️ Note: When using third-party apps to change system settings, make sure you download them from the official Google Play Store to avoid introducing malicious code. ☑️ Checklist before changing network settings Make sure network signal Check balance SIM-Maps Record the current number of the SMS center (if any)Know the exact number of the center of your operatorReboot the device after changes: 0 / 5 After a successful setting update, be sure to restart your smartphone.This is a critical step, as the Redmi communication module 9 reads SMSC at the time of the system launch. Without a reboot, the changes may not take effect and messages will continue to be sent through an old, non-working address. SIM-Default choice and cards by Xiaomi Redmi owner 9 frequently SIM-And then there's the nuance that every SIM has to have its own, correct SMS number, and a mistake in settings for even one of the cards can cause a crash if the system tries to send a message through it. MIUI You have a flexible messaging system, and you can assign what kind of message you want. SIM-The card is used to send by default, or to select it each time you write a new message. → SIM-maps and mobile networks. Here, in the "Default for calls" section/SMS», You can give priority. If you have a corporate SIM-card-card (MVNO), SMS settings may differ from standard ones, such as virtual operators operating on networks. Tele2 Or Megafon, which can use their own gateways, in which case the correct center number should be requested in the technical support of your specific operator, rather than looking at the common tables. 💡Use the “Block” feature in the standard Messages app to separate workers SMS Personally, if you use two SIM-cards for different purposes, and it is also worth noting that when you activate the service, "Super"-SIM» or switching to eSIM (if supported by the region and model), the profile of the SMS center can be overwritten remotely. If messages stop coming after replacing the physical card with eSIM, repeat the procedure of checking the center number, since the old profile could be preserved in the phone memory. Even with the correct number of the SMS center on Redmi 9, errors can occur, one of the most common is “Not delivered” with an error code of 12 or 98. This often indicates that the phone cannot register on the network to transmit service data, or is blocked by antivirus or system settings for energy saving. MIUI — It can put the Messages app to sleep, preventing it from connecting to the processing center. To rule out this factor, go to Settings. → Annexes → Communications → Battery and select "No Limits" mode». This will allow the application to always have access to the network. Another common problem is overcrowded message memory. Although modern smartphones have large amounts of memory, the internal database is overcrowded. SMS-Messages (especially if there are thousands of them) can cause service disruptions, cleaning up old dialogs or using a garbage cleaning app can restore normal operation. 🗑️ Remove dialog branches with a lot of attachments (MMS). 🔄 Clear the Messages app cache through the application settings. 📵 Check if the message center number is worth the Blacklist (rarely, but it happens when using third-party blockers). ⚠️ Note: If the message is not sent to only one specific number, the problem may not be in your SMS center, but that the recipient number is blocked or unavailable. Alternative methods and use of third-party applications If the regular means Xiaomi Redmi 9 You can't change the number of the SMS center (input fields are blocked in gray), you can resort to the use of specialized utilities «SMSC Updater or Force LTE Only (4G/5G/3G/2G)» You may need to use Root rights to access hidden radio module functions, but many of them can also work on standard firmware using debugging interfaces. Requests for broad permissions from unknown developers should be a cause for concern. In extreme cases, if the software methods do not help, you can use the command through the computer and debugging. USB (ADB). To do this, connect Redmi 9 to your PC, enable debugging mode, and type a command to update your network profile. ADB-adb shell service call sms 13 s16"+79168910000" Unskillful use ADB-The commands can cause the modem to crash software, so use this method only if you are sure of your actions. Why are the messages not coming, although the SMS number is correct? This can be due to locking on the operator's side (for example, for spam), overflow of memory. SIM-cards (old SIM cards store little) SMS) Or a temporary disruption of the operator's gateway, try sending a message to another subscriber to check. Does changing the SMS center affect mobile Internet? No, the SMS number (SMSC) It's only responsible for text messages. Mobile Internet is the responsibility of access point settings (APN). Both parameters are stored in the profile. SIM-And the cards can get lost at the same time when they're damaged. How do you know if you've received a message from the operator about the settings update? SMS from a short number (e.g. 111, 505, 800, etc.) and often marked as "Service" or not displayed in the shared feed, but immediately used by the system. Check the "Service" folder in the message application. Do I need to configure the SMS center for instant messengers (WhatsApp, Telegram)? No, SMS-center settings only apply to classic text messages (GSM). Messengers use mobile Internet or Wi-Fi channels and work regardless of the parameters. SMSC. Can a virus change the number of an SMS center? In theory, yes, malware with access rights to the SMS center? SMS It can redirect your messages to another number (for example, to steal confirmation codes from banks). Check your installed apps regularly and use antivirus.