Also known as a Delivery Reports, Message Confirmations or DLRs, is a report sent back by the mobile network that contains the outcome status of a message. It usually comprises 1 status for delivered messages and multiple statuses for failed messages. The following is an example non exhaustive list of outcomes:

• Delivered: SMS has been recorded as received from the Handset itself
• Failed : Absent Subscriber: Phone is switched off or unreachable by the operator
• Failed : Unknown Subscriber: Message is rejected – no directory number for the mobile subscriber
• Failed: SIM card full: No more messages can be delivered to the phone
• Expired: The maximum delivery period has been reached (usually 48 hours)