We may be able to help, but need to know exactly how are you sending those messages ??
Do you have an account with a Sms service provider or you used a GSM Modem, If it is the former then what type of connectivity have you used to send the messages (SMPP, HTTP API etc), without that information we can't help you much !!
Now since you are using HTTP to send messages, you need to consult your provider on how you can acquire the delivery report for messages at your end because unlike SMPP there is no standard HTTP API for sending messages and receiving delivery reports.
Getting the delivery report back from the provider depending on the provider may require you to create another web application onto which he may post the delivery reports of your messages.
Note: The only way to map a message correctly to its delivery report is through the Message Identifier which he(your provider) must be returning to you in the response when you originally submitted the message and also in the delivery report