If you're unable to send/receive SMS/MMS messages on your Redmi Note 11 Pro 5G, please refer to the following steps:
1. Ensure that you have sufficient credit to send/receive messages. You can contact your carrier customer support and see if your SIM card is out of credit;
2. Ensure that your phone's operating system is up-to-date. Software updates often include bug fixes, security patches, and improvements that can address software-level issues;
3. Make sure that the numbers and country code you are trying to send/receive messages from are correct, and ensure there are no spaces or special characters;
4. Make sure that the numbers you are trying to send/receive messages from are not blocked;
5. If you have access to another SIM card from the same carrier, try using it on your phone. If the issue is resolved, your original SIM card may be faulty. In this case, please contact your mobile carrier's customer support;
6. Insert your SIM card into another phone and check if you can send/receive messages. If the issue doesn't occur, please contact your seller or our local service center for assistance;
7. Restart your Xiaomi smartphone to refresh the operating system;
8. Clear the cache of your messaging app;
9. Ensure that your messaging app is set up correctly by going to [Settings] >> [Apps] >> [Manage apps] >> [Messages] >> [App permissions];
10. Check if the SIM card is in good condition by going to the [Phone] app and inputting *#*#6484#*#* or *#*#64663#*#* to enter the hardware detection (CIT mode). If there is a hardware issue, please contact our local official service center or your seller for further assistance. They will help you in this regard.
However, if there is no hardware issue, we hope you could submit user feedback by going to [Settings] >> [Services & feedback], and wait for the future updates.