Vonage SMS API will return Delivery Receipts (DLRs) for each SMS sent, whenever this is received from downstream carrier.
Each DLR will provide message status and an error code, which will indicate the delivery status of the specific SMS.
These are the statuses that can be expected to be returned in DLRs by Vonage SMS API:
There is a direct correspondence between these statuses (except ACCEPTD) and the columns found in our Dashboard SMS Delivery analytics section. See the table below for full information in each of the DLR statuses:
|Accepted||ACCEPTD||Message has been accepted on the network side and has been posted for delivery. This is an intermediate status which will be only present in intermediate DLRs.|
|Delivered||DELIVRD||Message reached the destination handset.*|
|Undelivered||UNDELIV||Message could not be delivered. Error code should provide more information on the reason.|
|Expired||EXPIRED||Message was held at downstream carrier’s retry scheme and could not be delivered within the SMS life-span.|
|Rejected||REJECTD||Message was rejected up-front by downstream carrier.|
|Deleted||DELETED||Message has been deleted from a queue. This normally happens when there is a queue on one gateway and SMSs are moved to a different gateway for delivery.|
|Unknown||UNKNOWN||Message is in invalid state and error code received was not known.
* In some instances DLRs are not a good indicator of SMS being delivered to the handset, and are merely a confirmation from the down-stream carrier of SMS having been posted for delivery to the network.