How do I implement an HTTP server or Web service in my VB ASP.Net App to receive SMS-MO messages via http API

Hi.

The above header refers.

I have a functioning VB Asp.net App that is Live @ http://www.234Aproko.com.

I have just subscribed to a short code and the provider needs to be sending SMS-MO Messages (periodically and as they occur) to me through my Asp.net App.

Now, I am able to send replies back to their server through the Web Client's downloadstring command.

The Issue I am having now is:

1. Which URL do they send their HTTP get requests to (this is their format: <base_url>?from=originator&to=shortcode/longcode&text=msgdata 
Other?

2. How do I listen (and how often) to be able to detect and receive such sent (SMS-MO) Messages, so I can I do what is required of my app?

If I didn't ask the right question, please pardon me.

Thanks.