We recently made a change to the status of text messages. Now we alert study staff if a text did not go through with the error we received from Twilio. Here are some common errors from text messages failing to be delivered through Twilio and what they mean:

• Error 30008 "Message Delivery - Unknown error": The carrier has returned a generic error message.
• Error 30005 "Message Delivery - Unknown destination handset": The carrier has reported the 'To' number is unknown, or no longer in service.
• Error 30003 "Message Delivery - Unreachable destination handset": The carrier has reported the 'To' number is unreachable - the device is likely powered down, out of the service area, or may not accept your messages.
• Error 30007 "Message Delivery - Carrier Violation": The carrier has filtered out your messages for delivery.
• Error 30004 "Message Delivery - Message blocked": Your message has been blocked from reaching the destination.
• Error 30006 "Message Delivery - Landline or unreachable carrier": The destination is a landline phone, or the destination carrier can't be reached.

If you encounter a message failure incident from Twilio that isn't on this list, please visit their website https://www.twilio.com/docs/api/errors#3-anchor to find out more.