Everything worth knowing, nothing that isn't.
The common states
Queued/accepted means the platform took the message; sent means it reached the operator; delivered means the handset confirmed receipt; failed/expired/rejected mean it did not arrive, usually with an operator error code explaining why. See /answers/what-is-dlr.
Sent is not delivered
A 'sent' status only means the operator accepted the message, not that it reached the phone. Only 'delivered' — with an operator-level receipt — confirms arrival, which is why transparent DLRs matter. See /answers/how-to-improve-sms-delivery-rates.
Act on the status
Read statuses in real time via a webhook so your application can retry failures, trigger fallback, or update the user. See /answers/what-is-a-messaging-webhook and /tools/dlr-decoder.