Redmi Note 4G : Signal or calling problems or cannot send SMS / MMS

How do I solve the problem of Redmi Note 4G version not being able to use 4G network? If you cannot use Redmi Note4G version 4G network, we recommend that you follow the following methods to troubleshoot: 
1 you need to replace to a 4G SIM card. To use the mobile version of 4G network on the Redmi Note 4G, you first need to apply for a replacement to a 4G SIM card if the SIM card cannot use ordinary mobile 4G network; 
2 There might be no 4G networks around that can use the 4G network coverage. If there are no 4G signals, the phone will automatically connect to 2G / 3G networks. 
3 Manually set 4G network priority, method to do so is: System Settings - Mobile Network - Network type selection -4G network priority. 

What do I do if my Redmi Note cannot send SMS / MMS? If your Redmi Note is unable to send SMS / MMS, we recommend that you try the following solutions: 
1 First, check the SMS center number is correct (correct SMS center number to be used with your network operator customer service); 
2 open always receive MMS options (System Settings - all settings - mobile network - always accept MMS "); 
3 To enable operators to make mobile Internet services available to you, MMS must have "mobile Internet" function under the premise that MMS can only be sent successfully if they do not charge traffic fees and only charge by the amount of MMS sent. 
4 If the Send MMS attachment is too large, operators generally will send MMS pictures under stringent size restrictions, consult specific operators for further details; 
5 Replacing SIM cards of different operators before trying to send; 
6 After upgrading to the latest version, backup beforing clear all data. Afterwards, try to send again; 
7 If the above methods do not work, it is recommended that you bring the phone to the nearest Xiaomi authorized repair point for testing.

What to do if Redmi Note has no signal? You can try to resolve using the following steps: 
1 Check if SIM card is correctly inserted and re-plug the card; 
2 Check if wrong SIM card is used. Redmi Note supports the use of mobile cards and Unicom card, but does not support the use of Telecommunications card; 
3 In the dial-up interface, enter "* # * # 64663 # * # *" into the hardware detection mode, open the SIM card test to detect SIM card status; 
4 Try replacing with another SIM card; 
5 If the show no signal, it is recommended that you bring the phone to the nearest Xiaomi authorized repair point for testing.

Why is there a countdown for Redmi Note 3G when making a phone call? If your Redmi Note is in dual SIM-card mode, you can directly enter the number to dial manually choose to use the SIM card 1 or SIM card 2 to call, such as clicking on a direct dial number in the call log or contact details, or go to the SIM card selection interface and confirm the SIM card to be used within 10 seconds of countdown. If selection is not done within 10 seconds, the phone will use the default method to call. 

Tips: If there is only one SIM card on the phone, you will not see this prompt.