What is the reason why Apple 6plus can't send text messages to others?

The SMS sent by Apple 6plus can't be received by others. Troubleshooting methods:

1. Make sure the signal is normal and close the flight mode.

2. Check whether the SIM card status is normal.

3. Check whether the send key is on and clickable.

4. If you can't click Send after entering the text, the "Send" key is still gray.

5. If you send text messages to multiple people and manually enter numbers, please make sure to separate each number by pressing line breaks instead of spaces.

6. If you can receive or send short messages, you can edit the number of the short message center through internal commands after eliminating the above problems.