Plivo sends SMS status codes at each stage of the delivery process. Depending on the message_state returned, we may also provide an accompanying error_code. For example, if delivery is unsuccessful when we try to deliver an SMS message to the carrier, the message_state will be updated from “queued” to “failed” and an accompanying error_code will be given.
If a message is successfully sent to the carrier, it can still hit roadblocks that cause it to fail. If the message_state changes from “queued” to “sent” and then to “undelivered,” we'll generate an error_code to help you learn more about a delivery issue.
This illustration shows a successful delivery path and the message_states that can occur.
See the list of Plivo error codes for outgoing and incoming messages.