After Unicom's 4G network was opened, the upper left corner became 3G, but it could not connect to the Internet, and the short message could not be sent or sent but others could not receive it. It's n

After Unicom's 4G network was opened, the upper left corner became 3G, but it could not connect to the Internet, and the short message could not be sent or sent but others could not receive it. It's no use changing cards. How come? If the mobile phone cannot use Unicom's 4G network, the following situations are not excluded:

1, 4G Internet access is not enabled;

2. The mobile phone does not support Unicom's 4G network, or the mobile phone you use only supports other operators' 4G networks and does not support Unicom's 4G network;

3. The location has not covered Unicom's 4G network.

4. The local city has Unicom's 4G network coverage, but the mobile phone is remote or the coverage is poor.

If your mobile phone can't send short messages, you can try to restart or change your mobile phone to test whether there are any of the following situations:

1. The SMS center number is set incorrectly, please re-enter the correct SMS center number;

2. No signal or low battery;

3. Because the system is busy during the holiday short message sending peak period, it is suggested that you try again later or avoid the sending peak period;

4. The sending format is incorrect. If you send a short message to PHS users, you need to add the area code before the number;

5. The short message sending time exceeds 24 hours;

6. The mobile phone shields the short message sending function;

7. Blacklisted by SMS;

8. Insufficient quantity balance;

9. SMS inbox and outbox are full.

If the above reasons cannot be solved, you can contact the local manual customer service or go to the business hall to confirm whether the SMS function is enabled and hand it over to the staff.