You can't send text messages if you change the mobile 2g card to the mobile 4g card. Is there any good way?

How to deal with the failure to send short messages after replacing 2G cards with 4G cards;

Check the signal status in the mobile phone. If the signal is weak or there is no signal, sending SMS will fail.

Check whether the security housekeeper in the mobile phone restricts the short message sending function;

Call customer service 10086 to see if the SMS function has been restricted, or go to the nearest mobile business hall to handle it;

Call customer service 10086 to check whether the mobile phone is in arrears. If it is in arrears, pay it in time;

Enter SMS settings and check whether the number of SMS center is set correctly. If you are not sure about the number of the SMS center, you can call customer service 10086 to get it.

If the mobile phone system does not respond, restart the mobile phone and send a text message;

Put the SIM card on other mobile phones to send short messages. If the SMS can be sent normally, it means that there is something wrong with the mobile phone itself, then take the mobile phone to the after-sales service point for repair or change it.