A text message in a campaign can fail due to the following reasons: 

1. Twilio rejects the number
2. Bad/ landline number

3. Message not sent by Twilio
4. Message sent but never delivered

5. Attachment file size exceeded

6. Geo permission issues for international SMS

7. The body exceeds the limit of 1600 characters

  • If you are using a trigger to send sms. Check the body of the message. Also, check to see if there is a custom value of {{message.body}}
    • For example, if someone replies via email and their email exceed the limit of 1600 characters, the message will not send if you have the custom value {{message.body}}

For more information on why a particular sms failed, check out How to check logs for a specific text message in Twilio