What hardware needed for establish own Short Message Service Center (SMSC) and SMS Gateway

Question

Dear All
I have developing SMS Application which Send and Receive SMS from Mobile and My Web Application.
2 way communication functionality in web application .

i have develop 2 way functionality by Third part Gateway provider by URL forwading option.
i its seem not secure , because it store all sms data on its database.

so i search lot for Create my own SMS Gateway or SMSC for send/receive sms.

but i cant find proper solution.

can you any one suggest how to create SMS GateWay or SMSC server ?
what hardware needed for this.?

i will pay for any hardware or software.

but i want to develop fully functionality without any other dependency.
and i want to develop web application with .net Framework 3.5 and advanced.
i will buy Sim card also if needed..

please give you valueable suggestion and help.
thanks in advanced.