If you want Delivery Reports (DLRs) use the premium=1 route (2c+GST extra per message).
OK:Queued:109720 - Message was added to the queue with message ID 109720
NOK:Funds:You do not have enough funds - Your account had insufficient funds
NOK:Login:Invalid Username or Password - Invalid username or password
The DLR URL is Optional, if you chose to use it we will post delivery reports for the message ID back to your webserver. You will need to create a delivery report page to capture the data and update your database.
220.127.116.11 - - [04/Apr/2012:08:24:45 +1200] "GET /delivery-report.php?id=109720&dlr=8 HTTP/1.1
18.104.22.168 - - [04/Apr/2012:08:24:52 +1200] "GET /delivery-report.php?id=109720&dlr=1 HTTP/1.1
As per above, we got 2 delivery reports for message ID 109720.
Reply messages will still be received via your registered email address however we will also call your DLR URL with the reply variable so you can process the reply internally to your CRM.
22.214.171.124 - - [04/Apr/2012:08:25:25 +1200] "GET /delivery-report.php?id=+109720&reply=Reply Text
DLR 16 - SMSC Rejected
DLR 8 - Message Queued
DLR 4 - Message Buffered
DLR 2 - Delivery Failure
DLR 1 - Message Delivered
Please note that sometimes a message may be delivered to the handset & have a DLR of 8 (Message queued) and may never get a DLR 1 (Message Delivered). This is not very common but can happen when overloading occurs on the destination SMSC. We have been told that
the provider would prefer to reserve resources to delivere messages rather than delivery reports.
You can check your balance with the API too, simply add &balance=true to the URL. For Example