These are the definitions for SMS-exclusive system statuses.

Accepted (Where the message is in the delivery process) - The message was accepted by the carrier.

Buffered (Where the message is in the delivery process) - The message is awaiting delivery.

Delivered (Where the message is in the delivery process) - The message was delivered to the carrier.

Expired (Where the message is in the delivery process) - The message has expired.

Failed to Send - The message failed to send.

Failed (Where message is in the delivery process) - The message failed to deliver.

New - A newly created SMS.

Rejected (Where message is in the delivery process) - The message was rejected by the carrier.

Sent - The message has been sent.

Unknown (Where message is in the delivery process) - An unknown error was received from the carrier who tried to send this message.