An SMS Software is needed which can send Branded SMS by using Internet Services. We dont need any GSM Device to send SMS.
we need everything with source code and with all the rights.
We can use that software as an online application, and as a desktop software and it can be customized easily
As per your requirement you have to buy bulk SMS from third party, and develop a software which will send SMS from the database as you require, it may be a windows application also. You will able to send SMS whenever needed. .NET will be better for it.
I have prepared a same software recently working in a govt sector successfully.