R – List all Alerts within a SharePoint site without using the SharePoint API

Based upon the information provided, I doubt this is a programming error. Can you get access to the IIS Manager interface on the server hosting the SharePoint site? If so, check the valid authentication technologies permitted. Are anonymous connections allowed? Is Windows Integrated Authentication enabled? HTTP Basic auth? Ask your infrastructure/SharePoint people about the possibility of a double-hop (proxy). If so, that might work too, but it's a pain to setup (Kerberos delegation). The NetworkCredentials class appears to support all of the standard authentication schemes supported by IIS (except for forms):

http://msdn.microsoft.com/en-us/library/system.net.networkcredential(VS.80).aspx

You might need to have the infrastructure people set SPNs for the SharePoint web front end:

http://support.microsoft.com/kb/929650

I advise against changing anything via IIS Manager, however. Have your SharePoint Admin make the changes to the authentication techs permitted for the site via SharePoint Central Administration.

Regards, Sam

I assume you've put the server name in that URL?

You should put the full path to the web service including server name, and after that convert it to a dynamic web service so that you can adjust the URL appropriately at runtime (through configuration or within the code).

If the path is correct (and full) then the connection should work fine.

If it still isn't working, consider whether you are connecting to the sharepoint instance via a proxy. Windows Authentication does not work over proxies due to the authentication token only being able to make one network hop... this is known as the double-hop bug. It's not really a bug, it's by design and is designed to prevent man in the middle attacks... so don't use a proxy.