SMS status - delivery receipt expired
Delivery receipt expired.
The SMS status 'delivery receipt expired' does not mean the messages were not successfully sent. This status basically means:
"The sender's carrier timed out waiting for the delivery receipt, this could be because the downstream provider did not send the requested delivery receipt, or they sent after it the system timed out at two hours".
So, although the messages would have been sent and received successfully, the receiver carrier failed to send the delivery report to the sender in the specified time period.