Chapter 18 covers how to access a service using Basic Authentication, but it leaves something very important out. It mentions setting up the client to use TransportCredentialOnly as the security mode and then in a side bar says that you should consider using this over SSL. Unfortunately TransportCredentialOnly does not allow SSL and you will receive an error if you try to use this with a https url. Instead you have to use Transport, in which case the credentials for Basic authentication will not be added to the header. You should refer to http://msdn.microsoft.com/en-us/libr...uritymode.aspx
for an explaination of how this works. Outside of Silverlight you can normally access the Transport property of the basicHttpBinding and set the ClientCredentialType to basic, but this property is not available to Silverlight and therefore is not available on the Windows Phone.
To get around this, I refer you to Chapter 14 and the section on custom headers. The only way I've found to allow Basic authenticaiton over SSL with a basicHttpBinding in Silverlight has been to add the Basic authentication header to the request myself.