Redmi mobile phone card slot sometimes (only sometimes) can't send short messages, open data, make phone calls and just don't display it.

Excuse me, which version of your mobile phone is and which carrier's network is used?

1, if it's not the reason of poor signal in your environment, please open Settings ~ Mobile Network ~ Network Type Selection ~ Only select 2G network and try to see if it can be used.

2. If it doesn't work, take out the sim card, reinstall it and try to use it.

3, still not working. I suggest you try another sim card.

4. If it still doesn't work, please take the phone to Xiaomi's authorized repair point or Xiaomi's home near you for testing.

Address and telephone number of authorized maintenance outlets: /c/service/poststation/.

Xiaomi Home Address and Telephone Enquiry /c/ Xiaomi Home

The working hours of Xiaomi House are from Tuesday to Sunday, 10 am to 6 pm.

The after-sales principle of genuine Xiaomi mobile phone, red rice mobile phone and Xiaomi tablet is non-artificial damage: return within seven days and replace within fifteen days.

During the one-year warranty period, non-man-made damage is completely free.

I hope the above reply can help you.