Delivery Notifications are message acknowledgments. When delivering messages through the Digital Interconnect network, customers can request to receive the following types of message acknowledgment: Digital Interconnect Ack, SMS-C Ack, Handset Ack. For unsuccessful delivery attempts, a negative acknowledgment (Nack) is returned outlining the reason for failure.
Note: Delivery notifications are an operator-dependent feature, and that not all operators support handset acknowledgments.
