I have added the intellisoftware dll to asp.net application using a generic handler (ashx) as the calling page. If I test this in visual studio on on PC this works and sends the SMS. If I compile and deploy the application to a shared server with IIS 6, I get the following error when calling the handler:

SMS Error Type: HTTP Error occurred trying to connecting to the IntelliSoftware gateway, see InnerException for details System.Net.WebException: The remote server returned an error: (407) Proxy Authentication Required. at System.Net.HttpWebRequest.GetRequestStream() at IntelliSoftware.Common.HTTPConnection.HTTPRequest(String sMethod, String sUrl, String sContentType, String sFormData) at IntelliSoftware.Internal.SMSGatewayService.MakeHTTPRequest(String sURL, SMSGatewayRequestData objSMSGatewayRequestData, String sReturnCodePrefix, String& sRawResponse, ResultCodes& ResultCode, Exception& InternalException)

I have tried routing the server so that it doesn't have to go through our proxy, and free access through the firewall and I get the same error. I can make changes to the website entry in IIS but I cannot make server wide changes as other web applications share the server.

If you are accessing our gateway from ASP.Net and your proxy server requires authentication, then HTTP access may be blocked. This is because the ASP.Net Worker Process is running as a local machine account (e.g. ASPNET). To fix this issue you can try running the ASP.Net Worker Process as your own personal domain account (please note this may introduce security risks).

http://support.microsoft.com/kb/895967 

I have tried setting up an application pool in IIS, and adding my domain account as the identity, then using this app pool with my application and I get the same message.