Q:

How to pass optional parameters for web method? 

I have a web method with multiple parameters.  The web method is only dependent on 2 fields, the rest are all optional. 
   [OperationContract]
    public string WarehouseContactInformation(int WAID (Required), string CN (Required), string CT (Optional), string CC (Optional), string CFN (Optional), string CD (Optional), string CE (Optional),string CW (Optional))

How to I declare these parameters as optional so that when I call the Web Method I only have to pass through the fields that i have values for, example:
WarehouseContactInformation(1,'Bill','00012311')
WarehouseContactInformation(1,'Bill','00012311','12415415','123525')

A:

You can't.  Web methods doesn't support optional parameters.  When you generate proxi for web method, you make get the specific signature, according to which you client and server would exchange the messages.  But it can't pass the optional parameters.  You can use default parameters on the server side, but no optional.