Invoking .Net Web Service with Php

I have a C#.Net Web Service and php client to invoke the web service.

Web Service Methods takes C# objects as parameters and returns C# objects as follows

Site getSite(siteID){ return Site.load(siteID) } 

or

void newSite(Site site){ site.save(); } 

I know that WSDL tool generates c# classes and java has code generator for web services.

• How can I invoke this services with Php?
• Is there any utilities, libraries, such as Pear, or any framework, like Zend, generates code for Php ?
• If I make the Objects in Php, and initialize them, then can i pass them to service calls and would that work?
• Should they be serialized ?