Message statuses

Status	Meaning
pending	Received by the API, queued.
scheduled	Scheduled with send_at.
sending	Picked up by the sending phone.
sent	Handed off to the carrier network.
delivered	Delivery receipt received from the recipient’s phone.
failed	Failed after all attempts. See failure_reason.
expired	Not sent in time (10 minutes by default in production, 60 s in the sandbox). Not charged.
received	Inbound SMS: a reply from a recipient.