For any distribution, the delivery export provides details on the status of delivery of each distribution message sent. There are instances when a particular distribution might have high number of ‘Failures’.
In the Delivery export, filter out ‘DeliveringFailed’ from the column ‘delivery state’. Corresponding error codes are shown in the column 'delivery_state_error_code'
This document explains the common error codes that we see during distribution of our chats. These error codes help us understand the reason as to why the message delivery failed.
Error 30003 and 30005
Unreachable destination handset
This means that the destination handset you are trying to reach is switched off or otherwise unreachable.
Possible causes are that the handset does not have sufficient signal, the phone number is prepaid and does not have sufficient balance or the number is no longer in use.
Error 30007
Message filtered
This means that the message content was flagged as going against the carrier guidelines and the message was blocked/filtered by Twilio or by the carrier.
Possible reasons could be that the message likely appeared to be spam, phishing, or fraud as per the carrier rules and regulations.
Error 30008
Message Delivery – Unknown Error
This means that the delivery of the message failed for unknown reasons.
It is a generic error returned from the carrier with no further details.
Error 21408
Permission to send an SMS has not been enabled
This means that you have attempted to send an SMS to a region that has not been enabled on the user’s phone.
It is possible that the phone number is currently in a region that is currently not supported by us.
Error 21610
Attempt to send to an unsubscribed recipient
This means that the person you are trying to message has opted out of receiving messages from your Twilio phone number or messaging service.
All the users associated with this error code have ‘Unsubscribed’ by responding STOP to the Twilio phone number.