Why can't Xiaomi 3 send text messages?

There are several reasons why mobile phones can't send text messages:

The center number in the 1) information setting is incorrect. You may have accidentally changed this value, so you can change it back. If you don't know the specific value, please call the local operator's toll-free number for consultation.

2) There are two possibilities for the SIM card (provided by the operator) in the mobile phone: first, the contact of the SIM card is dirty or the SIM card is loose; Second, the operator may stop your short message function because the operator suspects that you are sending business short messages. You can also consult the operator for free.