

Twilio rejects the number
Bad/ landline number
Message not sent by Twilio
Message sent but never delivered
Log into your Twilio account
Click the cog icon at top-right and choose Sub-Accounts then select the sub-account
Click the circle icon with three dots in the left column and select Programmable SMS
Click Logs then set your timeframe and filter by Status = Failed or Status = Undelivered
When you find the message, hover over the question mark icon to see error code/explanation


