To know whether your message has been delivered or not, follow these steps:
Login to your SMS panel.
Click on the SMS history link.
Now, you will land on a page where you will be able to see the status of every message that has been sent by you.
The status bar will show either of these results:
Delivered- It means the message has been duly sent and received.
Sent- The message has been sent but not it is yet to be received.
Failed- The message has been sent but couldn't get delivered due to unavailability of the number.
Rejected- The SMS has either been refused by the receiver's operating network, or by SMS Plus.